IED Attack: Improvised Explosive Devices

NEWS & TERRORISM

A fact sheet from the National Academies and the Department of Homeland Security

COMMUNICATING IN A CRISIS

IED ATTACK

IMPROVISED EXPLOSIVE DEVICES

WHAT IS IT?

An improvised explosive device (IED) attack is the use of a “homemade”

bomb and/or destructive device

to destroy, incapacitate, harass, or distract.

IEDs are used by criminals, vandals, terrorists, suicide bombers, and insur-

gents. Because they are improvised, IEDs can come in many forms, ranging

from a small pipe bomb to a sophisticated device capable of causing massive

damage and loss of life. IEDs can be carried or delivered in a vehicle; car-

ried, placed, or thrown by a person; delivered in a package; or concealed on

the roadside. The term IED came into common usage during the Iraq War

that began in 2003.

Elements of an IED

IEDs consist of a variety of components that include an initiator, switch, main

charge, power source, and a container. IEDs may be surrounded by or packed

with additional materials or “enhancements” such as nails, glass, or metal frag-

ments designed to increase the amount of shrapnel propelled by the explosion.

Enhancements may also include other elements such as hazardous materials. An

IED can be initiated by a variety of methods depending on the intended target.

Materials Used as Explosives in IEDs

Many commonly available materials, such as fertilizer, gunpowder, and

hydrogen peroxide, can be used as explosive materials in IEDs (see Table 1).

Explosives must contain a fuel and an oxidizer, which provides the oxygen

needed to sustain the reaction. A common example is ANFO, a mixture of

ammonium nitrate, which acts as the oxidizer, and fuel oil (the fuel source).

Concern about the use of explosives created from liquid components that

can be transported in a stable form and mixed at the site of attack is the

reason that in 2006 the U.S. Department of Homeland Security restricted

the amount of liquids that passengers can carry on commercial aircraft.

Table 1. Examples of explosives

Common uses Common form Known IED use

High explosives

Ammonium nitrate Mining and blasting

Solid Oklahoma City bombing

and fuel oil (ANFO)

Triacetone No common uses; mixed Crystalline solid 2005 bombings in London

Triperoxide (TATP) from other materials

Semtex, C-4 Primarily military Plastic solid Irish Republican Army bombings

Ethylene glycol Component of low- Liquid Millennium Bomber, intended for

dinitrate (EGDN) freezing dynamite Los Angeles airport, 1999

Urea nitrate Fertilizer Crystalline solid World Trade Center 1993

Low explosive

Smokeless powder Ammunition Solid Olympic Park bombings

The primary focus in this fact sheet is explosive-based IEDs; it does not address IEDs used for

dispersing chemical, radiological, or biological material, also known as “dirty bombs.” See the other

fact sheets in this series for information on chemical, radiological, or biological dispersion.

Amonium nitrate (without fuel oil) is used as fertilizer.

Examples of Terrorist IED Attacks

Oklahoma City Bombing

On the morning of April 19, 1995, a truck bomb

exploded in front of the Alfred P. Murrah Federal

Building in Oklahoma City, Oklahoma. The bomb

was improvised from ammonium nitrate fertilizer

and nitromethane, which were put into the back of

the truck and left to explode. It was the worst ter-

rorist attack on U.S. soil up to that time, killing 169

people. Timothy McVeigh was convicted and exe-

cuted for the crime; his accomplice, Terry Nichols,

is serving a life sentence in federal prison.

Madrid Train Attacks

Ten explosions rocked through four commuter

trains during rush hour on March 11, 2004, in

Madrid, Spain. The bombs had been made from

bags stuffed with explosives, allegedly the explo-

sive known as Goma-2 ECO, and metal fragments;

cell phones with timers were used to initiate the

explosive devices. The attack, which was car-

ried out by violent Islamist extremists, killed 191

people, and injured more than 1,800.

July 2005 London Bombings

Fifty-two people were killed and hundreds more

injured in a series of coordinated attacks on the

London transportation system on the morning of

July 7, 2005. The attacks were carried out by four

suicide bombers. Authorities had difficulty identify-

ing the explosive used in the IEDs; they believe

it was TATP on the basis of finding TATP in the

London apartment of the biochemist arrested in

Cairo in association with these bombings.

Olympic Park Bombing

In the midst of the 1996 Olympics, an IED com-

posed of “pipe bombs” concealed in a backpack

exploded in the Centennial Olympic Park in Atlanta,

Georgia, where the games were being hosted. The

bomb contained nails to increase its lethality. Two

people died and many were injured. Eric Rudolph

pleaded guilty in 2005.

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Limit your use of phones and other communications devices as much as possible, because com-

munications systems may become overloaded.

If you become trapped:

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Cover your nose and mouth with anything you have on hand to limit inhalation of dust or other

hazardous materials. Dense-weave cotton material can act as a good filter.

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Avoid unnecessary movement so you don’t kick up dust.

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Signal your location to rescuers by using a flashlight or whistle, or by tapping on a pipe or wall.

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Shout only as a last resort. Shouting can cause you to inhale dangerous amounts of dust and drain

your energy.

If you are nearby, but not at the immediate site of an attack:

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Assess the environment around you before taking any action.

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Avoid being lured closer to see what is happening because the risks from secondary attacks or

hazardous materials could be extremely high.

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Listen for, and follow, instructions from local authorities and building personnel. If no information

is immediately available from local officials, stay away from windows and doors and move to an

inner area of a building until directed differently by authorities.

If you are in a train, on the subway, or on a bus:

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In general, it is best to remain inside the train car unless you are in immediate danger.

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Use the communication system on the train car to receive instructions.

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If you are in danger and must leave the car, be aware of hazards on the tracks or in the tunnel and

move with caution to the nearest station or point where you can contact emergency personnel.

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Open windows or doors if possible and if it is safe to do so, because it can reduce the severity and

number of injuries from a secondary explosion.

Caring for the injured:

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First aid you provide may save lives. The most likely help you may need to provide is to control

bleeding. Apply direct pressure to the bleeding site.

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Nearby hospitals may be overwhelmed with victims. If you need to transport victims who are not

severely injured, go to a hospital that is further from the bombing site.

ADDITIONAL INFORMATION

U.S. Department of Homeland Security – http://www.dhs.gov and http://www.ready.gov

Federal Bureau of Investigation – http://www.fbi.gov

Federal Emergency Management Agency – http://www.fema.gov

U.S. Department of Health and Human Services – http://www.hhs.gov/emergency

Centers for Disease Control and Prevention – http://emergency.cdc.gov

Bureau of Alcohol, Tobacco, Firearms, and Explosives – http://www.atf.gov

Technical Support Working Group, Improvised Device Defeat Subgroup – http://www.tswg.gov

Local and state government websites often contain information regarding emergency preparedness and response to

mass casualty events, including IED attacks.

This report brief was prepared by the National Academy of Engineering and the National Research Council of the

National Academies in cooperation with the U.S. Department of Homeland Security. For more information, contact

Randy Atkins at 202-334-1508, [email protected], or visit www.nae.edu/factsheets.

WHAT SHOULD PEOPLE DO TO PROTECT THEMSELVES?

The number one way to protect yourself and others from an IED attack is to be alert to your sur-

roundings. Advanced technologies help police and other authorities detect possible dangers, but

an even more effective tool is to encourage individuals to be alert for, and to report, anything that

is out of the ordinary in their daily routine. Examples include bags or boxes in unusual places,

unusual smells, and suspicious behaviors such as someone dressed in a heavy coat in summer.

Steps to Take if You See Something Suspicious

“If you see it, say it!”

It can be difficult to determine when to report something suspicious. People most familiar with a

given environment are in the best position to determine whether or not something is out of the

ordinary. Use common sense, and follow these guidelines:

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Trust your instincts; if something feels wrong, don’t ignore it.

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Do not assume that someone else has already reported it.

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Call local authorities.

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Keep your distance from a suspicious package—do not approach or tamper with it.

When you make a report, be ready to provide your name, your location, a description of what you think

is suspicious, and the time you saw it. The responding officer will assess the situation, ensure the area

is evacuated and call for appropriate personnel and equipment. Technologies used to assess whether a

package contains explosive material may include portable x-ray systems or bomb disposal robots.

Make a Personal Plan for Response

Preparation is key. Every person can take these steps to prepare for an IED attack:

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Learn the emergency procedures at your place of work, any other sites you visit regularly, and

any public transportation systems you use. Communication systems may be inoperable in an

emergency, and you should be familiar with what steps to take.

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Know how to get out of the area. If you work far from home, plan backups to get home if the

usual modes of transit are not operating.

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Know the routes to hospitals in your community.

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Take a first aid course.

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Make a family emergency plan. Remember that family members may be in separate locations

at the time of an attack. Use planning tools at ready.gov to prepare yourself and your family,

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Designate an “out-of-area” contact, and make sure that everyone in your family has that

person’s phone number.

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Have an emergency supply kit at work and at home that includes water and non-perishable

food to last at least three days, battery-powered radio, first aid kit, flashlights, and batteries.

WHAT TO DO DURING AN IED ATTACK

If you are at the immediate site of an IED attack, your top priority is to get out of the area.

This increases your safety in case a secondary device is present in the area and minimizes your

exposure to dust, smoke, and any hazardous substances that may have been released as a result

of the blast. This also allows emergency responders to find and assist the most critically injured

victims.

If you are in a building:

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Get under a sturdy table or desk if objects are falling around you.

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Exit as quickly as possible, without stopping to retrieve personal possessions or make phone

calls. Assist other victims to leave the area if possible. Use stairs instead of elevators. Be aware

of weakened floors and stairways, and watch for falling debris as you exit the building.

Once you are out of the building:

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Move away from windows, glass doors, or other potentially hazardous areas.

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Continue moving away from the blast site and look for emergency officials who will direct

you to a safe location.

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Be aware that secondary explosions may occur at or near the original bombing site, especially

as rescue personnel arrive. Use caution to avoid debris that could be hot, sharp, or cause

puncture wounds.

WHAT ARE THE EFFECTS?

The extent of damage caused by an IED depends on its size, construction, and placement, and

whether it incorporates a high explosive or propellant. Table 2 predicts the damage radius based

on the volume or weight of explosive (TNT equivalent) and the type of bomb. Vehicle bombs,

also know as vehicle-borne IEDs, can carry significantly more explosive material, and therefore

do more damage.

Damage to Structures and to Infrastructure

An explosion in or near a building or public transportation venue may blow out windows; destroy

walls; and shut down building systems such as power, ventilation, fire suppression, water/sewage, and

others. Exit routes may be disrupted or destroyed, and smoke and dust may travel upward through stair-

ways and elevator shafts, making navigation difficult. Building

failure may result in the release of hazardous materials used

within a building, such as radioactive material from medical

devices, or incorporated within the structure of a building,

such as asbestos insulation. An IED attack may cause disrup-

tions in municipal services such as electricity, water, commu-

nications, and transportation, which may continue for days to

weeks after the attack. Individuals and businesses should have

a plan for addressing these interruptions.

The Possibility of Secondary Devices

and/or Multiple Explosions

A known bomber tactic is to use a distraction, such as gun-

fire, small bombs, or other surprises, to attract bystanders

to a window, a doorway, or outside, and then to detonate

a second destructive device at the gathering point. In an

attack, there may be bombings at multiple locations. Rescue efforts can be hampered by the need

to respond to more than one site.

Secondary Hazards

The explosion of a bomb can cause secondary explosions if gasoline, natural gas, or other flammable

material is ignited. Secondary hazards that result can include fire with possibly toxic smoke, disrup-

tion of electric power, ruptured natural gas lines and water mains, and debris. There can be loss of

traffic control in the area of the blast with possible traffic accidents involving fleeing citizens.

Immediate Health Effects

Explosions create a high-pressure blast that sends debris flying and lifts people off the ground. The

type of injuries and the number of people hurt will vary depending on: the physical environment

and the size of the blast; the amount of shielding between victims and the blast; fires, or structural

damage that result from the explosion; and whether the explosion occurs in a closed space or an

open area. Injuries common to explosions include:

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Overpressure damage to the lungs, ears, abdomen, and other pressure-sensitive organs. Blast

lung injury, a condition caused by the extreme pressure of an explosion, is the leading cause

of illness and death for initial survivors of an explosion.

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Fragmentation injuries caused by projectiles thrown by the blast – material from the bomb,

shrapnel, or flying debris that penetrates the body and causes damage.

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Impact injuries caused when the blast throws a victim into another object, i.e. fractures,

amputation, and trauma to the head and neck.

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Thermal injuries caused by burns to the skin, mouth, sinus, and lungs.

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Other injuries including exposure to toxic substances, crush injuries, and aggravation of pre-

existing conditions (asthma, congestive heart failure, etc.).

Delayed Health Effects

Some health effects caused by IEDs, including eye injuries and abdominal injuries, may not be

apparent initially, but can cause symptoms and even fatalities hours to months after the event.

Psychological effects in attack survivors, first responders, and others are not unusual in the after-

math of a high-casualty event. While most symptoms diminish with time, in some cases assistance

and guidance from mental health professionals may be required.

Table 2.

Courtesy U.S. Technical Support

Working Group (TSWG)

The number one way

to protect yourself

and others from

an IED attack is

to be alert to your

surroundings.

Detecting IEDs

Detection of IEDs presents a real

challenge for security screeners,

employees, first responders, and

military personnel. Training secu-

rity guards, airport staff, and other

personnel to be alert for suspi-

cious behavior and IED indicators

is the most common and best

defense. Various bomb detection

technologies continue to be devel-

oped for use in high-risk areas

or situations such as airports and

high profile events. These tech-

nologies include “trace detectors”

that identify trace amounts of com-

monly used explosives in the air,

and “millimeter-wave technology”

that detects dense objects, hidden

under clothes. Explosives-detection

dogs, trained to detect and locate

chemical explosives, are used in

many security scenarios.

If You are a Business Owner

Be aware. Many commercial products

can be used to construct IEDs. Here

are some simple steps you can take to

avoid unwittingly enabling an attack:

• Recognize hazardous chemicals in

your

product inventory.

• Check your inventory and report

miss

ing or stolen products.

• Ask for customer identification and

main

tain a log of large purchases.

• Know your customers and report

susp

icious or unusual purchases to

autho

rities.

• Watch for suspicious behavior, which

can

include:

– Nervousness.

– Vague knowledge of a product’s

pro

per use.

– Purchasing unusual quantities of

a p

roduct.

– Large cash purchases.

– In storage facilities, custom-

ers

utilizing a facility at unusual

hours; odors, liquids, or fumes

coming from a storage unit; dis-

carded chemical containers.

FBI-DHS offers advisory materials for

the private sector.