A 52-year-old Niagara Regional Police officer sustained critical injuries from a gunshot wound after an altercation between two cops took place on Thursday afternoon.

The incident took place in Pelham, Ont., about 30 minutes west of Niagara Falls. The Special Investigations Unit has invoked its mandate.

“The preliminary information indicates that earlier today officers were in the area of Effingham Street and Roland Street conducting an investigation into a collision that occurred days prior,” SIU spokesperson Monica Hudon told reporters at the scene on Thursday night.

“Around noon there was an interaction between two officers and one of the officers was struck by a gunshot.”

The officer was transported to a hospital to be treated for his serious injuries and then was airlifted to a Hamilton trauma centre, where he remains.

The SIU is an arm’s length agency called in to investigate whenever police are involved in a death, serious injury or allegations of sexual assault.

Eight investigators and three forensic investigators with the SIU have been assigned to this case.