CALGARY - Two officers who work for Alberta's police investigative unit were injured at its downtown Calgary headquarters Tuesday when a witness pulled out a knife.

RCMP Supt. Randy McGinnis said there was a struggle in an interview room at the offices of the Alberta Serious Incident Response Team.

He said one officer was taken to hospital in serious condition, and another had cuts to his hand.

Calgary police confirmed the more seriously injured officer was stabbed three times and had life-threatening injuries, although his condition was later upgraded to stable.

"Initial indications — and this is very initial — is that it was serious," Duty Insp. Darren Cave of the Calgary Police Service said.

"We have one person in custody so ... it is under control."

The investigative unit, called ASIRT for short, reviews incidents or complaints involving serious injury or death that may have resulted from the actions of a police officer.

Police said a civilian witness, a 30-year-old man who is known to them, had been escorted to an interview room by a plainclothes Mountie working with ASIRT. That's when the man attacked the officer.

Other members from the ASIRT team heard the commotion and rushed to intervene. They took the man into custody. McGinnis said the suspect was bumped on the head. City police said he was taken to hospital with undetermined injuries. Photos showed him being taken out of the building on a stretcher.

It was one of the intervening officers, a member of the Calgary Police Service who is assigned to ASIRT, who was cut on the hand.

When reached on his cellphone immediately after the attack, Clifton Purvis, who heads the investigative unit, said he would be releasing more information later in the day.

ASIRT has jurisdiction over all sworn police officers in the province and has offices in Edmonton and Calgary.

Purvis, a lawyer and Crown prosecutor, is ASIRT's civilian director. Besides several other civilian analysts and investigators, there are 10 police officers on the team.

The team's Calgary headquarters is housed in an office building next to the law courts along the city's C-Train line. There are various other government offices in the building. The city's drug court also calls the building home.

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