Security footage obtained by the Globe shows a panicked crowd fleeing the Chick-fil-A restaurant in Copley Square Saturday evening at about the time an off-duty police officer shot and killed a person police say was wielding a knife and trying to stab people.

The knife-wielding attacker shot and killed by an off-duty Boston police officer after refusing to back down from terrorizing Chick-fil-A patrons in the Back Bay this weekend has been identified.

The Boston Police Detectives Union praised the actions of an off-duty officer who authorities say shot and killed a knife-wielding suspect​ inside a city Chick-fil-A.