Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link
Quick Facts

Mass Casualty Weapons


The Manual's Editorial Staff

Last full review/revision May 2021| Content last modified May 2021
Click here for the Professional Version
Get the full details

What is a mass casualty weapon?

A casualty is a person hurt or killed by a dangerous event. Mass casualties are when many people are hurt all at once. Mass casualties can come from big accidents, such as a bad train crash, collapsed building, or chemical spill. Mass casualties also can come from intentional events, such as wars or terrorist attacks. Intentional attacks use mass casualty weapons, such as explosives, chemicals, and germs.

Mass casualty weapons are sometimes called weapons of mass destruction (WMD).

  • A mass casualty event is when more people are injured than nearby rescue squads, doctors, and hospitals are normally able to care for at one time

  • Hospitals and communities plan ahead for possible disasters so they'll have enough staff, supplies, and equipment on hand and know how to respond

What are types of mass casualty weapons?

Types of mass casualty weapons include:

Contamination is a problem with many types of mass casualty weapons.

  • Contamination is when people or the area they're in are covered with a dangerous substance, such as a chemical or radioactive material

The dangerous substance might keep affecting the person until it is removed (a process called decontamination). Also, the dangerous substance can spread to rescuers and, depending on what it is, to nearby areas in the community.

How do doctors know an event involving mass casualty weapons has taken place?

Sometimes the event is obvious, such as an explosion or chemical spill. Other times doctors don't realize mass casualty weapons have been used until many people get sick at the same time in the same place. Doctors come to realize mass casualty weapons were used because:

  • Many different people all have the same unusual symptoms

  • The people who created the attack announce it

  • Environmental changes (such as unusual smells or dying animals) offer clues and raise suspicions

How do doctors and first responders deal with mass casualty weapon attacks?

Preparation is critical. Before any event, communities and hospitals:

  • Create a written disaster plan so everyone knows what to do

  • Make sure there are ways to quickly bring in extra personnel, including police, paramedics, and doctors

  • Make sure there are plenty of medical supplies and protective equipment stored away, ready to be brought out

  • Make arrangements with nearby hospitals and communities to provide help if needed

  • Do practice drills on how to respond to a mass casualty event

State and federal governments also have plans for helping communities respond to a mass casualty weapon attack.

Right after an attack, emergency responders first check to see if the scene is still dangerous, such as with:

  • Attackers on the scene

  • Unexploded bombs

  • Dangerous chemicals or radioactive materials on the ground or in the air

Checking for continued threats lets responders know what protective gear or personnel are required to make it safe to look for and treat casualties.

If contaminating substances were involved, first responders:

  • Estimate how big the danger zone is

  • Protect themselves from injury by staying out of contaminated areas unless they are wearing protective gear

  • Establish an area outside the danger zone for decontaminating people and another area for treating them

When it is safe to go to the injured people, first responders:

  • Do triage, which is quickly checking each casualty to decide how soon they need medical care

  • Begin removing people who need immediate medical care

  • Tell injured people who can walk to go to the treatment area on their own

It's important for first responders doing triage to check everyone first and not just start treating the first casualty they see. Checking everyone makes sure that they find all the people with reversible life-threatening injuries who might be saved with immediate treatment.

When many people are seriously injured and near death, some who might be saved if they were the only injured person may have to be left until there's time to treat them. That's so that doctors can work on people who are more likely to live.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
Others also read
Test your knowledge
Vitamin B6 (Pyroxidine)
Vitamin B6 (pyroxidine), an essential vitamin, is needed to process (metabolize) carbohydrates, amino acids, and fats; facilitate healthy nerve function; form red blood cells; and maintain skin health. Vitamin B6 is in many foods. Which of the following is NOT a good source of vitamin B6?
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID