CHICAGO -- Chicago first responders staged a large-scale active shooter drill at Wrigley Field today.
They simulated a situation in which gunmen get past the metal detectors and start firing at people inside the ball park.
About 100 police recruits posed as fans in the mock scenario. Some pretended to be injured by the gunmen, allowing emergency responders to practice how they would deal with a mass shooting situation.
Officials say the key in any active shooting scenario is the immediate response which often involves the closest beat cops, before the specialized SWAT teams arrive.
Chicago firefighters and police officers, as well as the city's emergency office and the Chicago Cubs were involved.
Chicago police say the drill was planned months ago to coincide with Major League Baseball's All-Star break this week. Cubs spokesman Julian Green says the team is happy to partner with law enforcement on the exercise to ensure a safe and secure environment.
Chicago police have held similar drills at other large venues.