It was a dark day for policing in Niagara Region and the rest of the province.

A Niagara Regional Police constable was in grave condition after being shot in an altercation with a fellow officer who outranked him.

The shooting, sources say, followed a “heated argument” and “fist fight” between a constable and a detective sergeant responding to a traffic accident around Roland Rd. and Effingham St. in Pelham, 22 kilometres south of St. Catharines.

Wounded Const. Nathan Parker was in hospital fighting for his life Thursday while Det.-Sgt. Shane Donovan was determined to be the subject officer by the province’s Special Investigations Unit (SIU).

Sources told theToronto Sun that Donovan was losing a fight before the shooting. Up to five bullets were allegedly discharged from a police officer’s gun.

There have been accidental shootings of police officers by their partners but in his more than 50 years as a Toronto Police officer, newly-named OPP Commissioner Ron Taverner, currently a superintendent, said he can’t recall ever hearing of a case where an officer shot a peer.

“It’s very sad and our thoughts are with the Niagara Police today,” he said.