A lone gunman opened fire and killed five people at a Toronto-area condo building on Sunday evening before he himself was shot by police, the regional force's chief said. 

Jim MacSween, head of the York Regional Police Force, offered few details in the hours immediately following the shooting in Vaughan, Ont. But in a hastily called news conference outside the building, he said police immediately realized a complex situation was unfolding. 

"Once the officers arrived they were met with a horrendous scene," he said. "Numerous victims were deceased."

MacSween said officers were called to what he described as an active shooting at around 7:20 p.m. In a separate news release, York Police said early reports suggested a man had shot multiple people. 

MacSween confirmed there were a total of five victims, but provided no details as to their identities or ages as family members were still being notified.

MacSween said officers eventually found the gunman. 

"There was an engagement between the officers and a subject. ... After the engagement, the subject was deceased as well," he said, providing no other details as to what took place. 

MacSween said Ontario's Special Investigations Unit — the oversight body that probes all police-involved incidents in which someone is killed or injured — will probe the interaction between police and the suspect. York Police's homicide unit will handle the investigation into the other five deaths. 

MacSween said the shooting also sent one person to a local hospital. 

The force's emergency response unit cleared the building as part of the investigation, though MacSween said they're working to ensure residents can return as soon as possible. 

The chief said police do not believe there is any ongoing risk to public safety.

"Right now we just offer our sincere condolences to the victims' families," he said. 

This report from The Canadian Press was first published Dec. 19, 2022.