Off-duty Boston police officer kills knife-wielding suspect inside Copley Square restaurant

An off-duty Boston police officer shot and killed a man who was armed with a knife inside a Copley Square restaurant Saturday, according to police.

Boston Police Commissioner Michael Cox said the officer took action after the suspect, wielding a knife, chased two people into the Chick-fil-A restaurant on Boylston Street around 5:30 p.m.

"The off-duty officer identified himself as a police officer, instructed them to drop the weapon, at which point the individual did not comply. The officer discharged his weapon to stop the threat and the individual was struck," Cox said.

The suspect was pronounced dead at the hospital. The officer was not hurt but was taken to the hospital as a precaution.

Suffolk County District Attorney Kevin Hayden said they do not know the motive for the attack.

"We're reviewing a large amount of video evidence in and around this area ... and we have reason to believe ... that there are other individuals who know something, who witnessed something, who may have been involved," he said.

Boston Mayor Michelle Wu spoke with reporters outside the restaurant following the shooting.

"I'm glad that the officer is safe, and very grateful for a quick response from all of our first responders here in such an active part of Boston," she said.

Cox commended the police officer.

"We don't look for loss of life," Cox said. "Our condolences go out to the family of the individual. We are also proud our police officers, whether on-duty or off-duty, who activate themselves to help save lives."

Wu said the violence is unsettling for the community.

"We know that anything like this that happens, any incident of violence is deeply impactful," she said.

A section of Boylston Street was closed for several hours Saturday night while police investigated.