TORONTO (AP) — A 73-year-old man shot and killed five people on several different floors of a suburban Toronto condominium building before police officers killed him, authorities said.

Police said the officer fatally shot the gunman inside the building, which is where the gunman lived and is in Vaughan, Ontario.

Police did not disclose a possible motive for the attack or release the names or ages of anyone who was killed, including the alleged assailant’s. But Ontario’s Special Investigations Unit, which gets involved when there is a death or serious injury involving police, said Monday that the attacker was 73.

SIU spokespeson Kristy Denette said police found the victims on different floors. She could not say whether they were killed inside of their units or at their doors.

Denette said the SIU wouldn’t release the attacker’s name because his family hadn’t agreed to it. She said he had a semiautomatic handgun and that investigators don’t believe he exchanged fire with the officer who killed him.

“Horrendous scene,” Chief James MacSween of the York Regional MacSween said late Sunday. “Six deceased. One of them is the subject. The other five are victims.”

One person who was shot by the attacker was hospitalized and was expected to survive, the chief said.

MacSween said he didn’t know whether the shooter lived at the condo building.

York Regional Police say officers were called to the Vaughan, Ontario condo for an active shooting around 7:20 p.m. Sunday.

Police evacuated the building on Sunday, but MacSween said there was no further threat to the community. Residents were allowed to return home early Monday.

Resident John Santoro said police went floor to floor to try to find out if anybody else was involved.

“When I opened my door, police were in the corridor. There were two officers right outside my door in the elevator lobby,” he said.

Mass shootings are rare in Canada, and Toronto has long prided itself as being one of the world’s safest big cities. Vaughan is just north of Toronto.

Canadians are nervous about anything that might indicate they are moving closer to the gun violence situation in the U.S., where mass shootings are common.

“Everybody is horrified,” Vaughan Mayor Steven Del Duca said. “To wake up to this news this morning or see it last night, we are in absolute shock. … This is something I never thought I would see here.”