What is a mass casualty incident?

ROWLEY, Mass. — Some people have taken to social media to voice their concerns about the local news media using the term ‘mass casualty incident’ to refer to a gas leak at the Market Basket in Rowley.

“You hear mass causality you think something worse,” one Twitter user wrote.

Another Twitter user commented, “It’s a contained gas leak, hardly a “mass casualty,” language like that leads people to jump to conclusions and scare them.”

So, exactly what is a mass casualty incident?

Here’s a little background on how the event unfolded in our newsroom: A viewer called us around 3 p.m. on Thursday to alert us to the gas leak. Our assignment desk immediately started reaching out to authorities to get confirmation.

Rowley Police informed us they were responding to a ‘mass casualty incident’ at the Market Basket on Route 1.

Many people often associate the word casualty with death, however, the word casualty also encompasses people who are injured.

The DelValle Institute Learning Center, the training branch of the Boston Public Health Commission's Office of Public Health Preparedness, defines a 'mass casualty incident' as:

"Although many have attempted to put numbers to what constitutes a mass casualty incident (MCI), perhaps the best definition is any number of casualties that exceed the resources normally available from local resources. This is based upon available resources, number of injuries, and severity of injuries. For example, in your response system, 20 victims with minor injuries may not require instituting the MCI plan, while five victims with critical injuries may."

According to an article in the U.S. National Library of Medicine, a 'mass casualty incident' is:

"an event that overwhelms the local healthcare system, with number of casualties that vastly exceeds the local resources and capabilities in a short period of time."

Rowley’s police and fire chiefs later informed us eight people were taken by ambulance to area hospitals and more than 50 were evaluated at the scene for respiratory issues. As good as Rowley’s first responders are, there’s no way they would have been able to evaluate and treat each one of those patients on their own in a timely manner, which is why they declared a ‘mass casualty incident’ and requested numerous agencies respond to the scene.