24-Hour Security Exercise Held Around Boston This Weekend

Don't be alarmed this weekend if you see SWAT teams and bomb squads swarming around Boston, first responders in hazmat suits near subway stations or hostage negotiators at City Hall.

These real-life scenarios are part of an exercise called Urban Shield Training.

"The Urban Shield, as we've learned over the past year, is essential to our city's safety in the time of crisis," Mayor Marty Walsh said in discussing the program Thursday morning.

The 24-hour exercise begins Saturday at 8 a.m. and ends Sunday at 8 a.m.

This is the third year Urban Shield will be held in Boston, and it'll be the largest public safety training program ever conducted in the city.

Over 2,000 first-responders from 14 area hospitals and 60 federal, state and local agencies will participate. During the exercise there will be more than a dozen emergency simulations. The exact scenarios are secret but promise to be "scary real," officials said.

"Over 24 hours we're gonna test our capabilities on incidents such as active shooter, building collapses, hospital evacuations and terrorist attacks," Boston Police Commissioner William Evans said. "So this has become an important part of how we train for the unforeseeable."

After last year's marathon bombing, Boston got a 60 percent boost in federal money for this year's Urban Shield exercise, which is funded by the Department of Homeland Security.

Eight communities around Boston — Brookline, Cambridge, Chelsea, Everett, Quincy, Revere, Somerville and Winthrop — will participate, each contributing special expertise.

Police Lt. Bob Gillan says Quincy K9s will be out in force.

"The city of Quincy has six bomb detection dogs," he said. "And so this region has the largest pool of bomb detection canines in the country."

Per Boston Police, emergency scenarios will be held at the following locations: