BALTIMORE (WJZ)-- Lights and sirens lit up North Baltimore Sunday morning but not for a real emergency.

First responders from all over the region came together for a mass casualty simulation training exercise at Pimlico Racecourse.

"This is about as realistic as it gets," said Scott Goldstein of the Pikesville Volunteer Fire Company.

The elaborate mass casualty training exercise is meant to prepare first responders to stay clam in the chaos of a deadly attack.

"So, based on what we see going around the world today, this falls right into play with what we're seeing," Goldstein added.

The story line--including drug overdoses, a car driving into the infield and an active shooter--is not unlike the Las Vegas shooting, where more than 50 people were shot dead from a hotel room above.

Doctors and nurses at Sinai Hospital are preparing to take in waves of patients.

"So we train in silos. Fire department does their drills, hospital does their drills. This is the first time we've trained together with the hospital and the fire department," said Martha Hill of Sinai Hospital.

For the volunteer actors--it's very real and eye opening.

"It was mayhem. I was supposed to be paired with somebody who wasn't really my daughter and you would lose people in like, seconds. I'd turn around and she was gone," volunteer Jane Allgair said.

These are skills first responders hope they'll never have to use. But Baltimore is more ready now for the worst case scenario.

"It's not "if", right, it's "when." So we're just waiting for an event like this to happen in our own backyard. And when it does, we'll be more prepared because of drills like this," Hill said.

About a dozen agencies participated in the drill, including firefighters and paramedics from counties surrounding Baltimore.

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