A mass casualty drill is being held at the Indiana State Fairgrounds Tuesday, just a day after the Boston Marathon bombings.

While the hope is that those real-life scenarios will never unfold, first responders around the country train specifically for events like the one that happened in Boston Monday.

Tuesday in Indianapolis, first responders trained for a mass casualty incident. People played the role of the injured and SWAT teams played roles in extracting the "injured" from an unknown explosion and partial building collapse in Castleton. (Note: This was a drill. There has not been any incident today.)

"It's an ongoing effort on our part to make sure our skills are up to date whenever we have a situation like they had in Boston or anywhere else. We want to make sure our officers are prepared to respond the proper way to help save people," said Lt. Chris Bailey, Indianapolis Metro Police.

Indianapolis is no stranger to hosting big events, including the 2012 Super Bowl, the Indianapolis 500 and the Mini Marathon. It's also seen mass casualty incidents like the Indiana State Fairgrounds stage collapse in 2011 and the Richmond Hill explosion in 2012.

"These are the guys that you would have seen respond to the Richmond Hills explosion, the guys that put together teams of three and four, went into the explosion area, went into houses and tried to get people out," said Lt. Bailey.

Indiana Homeland Security, IMPD and other police agencies are training over the next seven days at the fairgrounds. The training is one step toward adding more than 100 newly trained officers to run into burning buildings - or towards the scene of any disaster - when you need them.