WASHINGTON — More than 400 individuals will take part Sunday in an emergency drill in D.C., testing first responders’ ability to quickly and effectively react to multiple terrorist attacks.

“One that happens on a federal installation and the other will happen at a facility that we’re calling mixed used — retail on the bottom, upstairs having residences,” says Chris Geldart, director of D.C.’s Homeland Security and Emergency Management Agency.

The drill, which has been in the works for more than six months, will occur on the grounds of the former Walter Reed Army Medical Center.

“Everybody needs to practice, everybody needs to rehearse,” Geldart says.

The goal of the exercise is to ensure that agencies are ready to respond to any terrorist attack in the city.

The exercise has been scheduled at night to minimize impact on traffic and local operations.

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