LAUREL, Md. (AP) — The car jolted as protesters pounded on its windows, boxing in the lawmaker trapped inside. Within seconds, officers in full riot gear surged forward in formation, yanking open the doors and pulling the passenger to safety. A few hundred yards away, another team of police moved just as quickly, surrounding, isolating and arresting a man spotted in the crowd with a gun.

The clashes were staged, unfolding Friday at a Secret Service training complex in Maryland. The U.S. Capitol Police led the operation, joined by 600 officers representing nearly 20 agencies — including the Secret Service and local police and sheriff’s departments — in one of the largest law enforcement training drills in the country. The goal was to sharpen coordination among the many agencies that must w

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