An early morning home invasion left one person with a serious gunshot wound to the head at what police say was a marijuana grow-op in the city's east end.

Police responded to an ambulance station on Sheppard Ave. E. in Scarborough just before midnight. A man suffering "an obvious gunshot wound" had been left in the parking lot, police Const. Wendy Drummond told CTV.ca.

Subsequent investigation led police to a nearby home at 233 Dean Park Road, in the Sheppard and Meadowvale area.

Police allege that three people, armed with handguns, burst into the home in the quiet residential neighbourhood. Investigators believe a struggle ensued between the armed men and the occupants.

One of the home's four occupants was shot in the head during the struggle.

In a written statement from police released Thursday afternoon, police said the occupants were "restrained" while the suspects "removed a quantity of marijuana."

Investigators believe the house was the site of a marijuana grow-op.

When the armed suspects left the scene, one of the occupants managed to call a friend instead of calling for an ambulance.

The unidentified friend brought the injured man to the ambulance station, leaving him in the parking lot. The victim, identified as Khong Duy Nguyen of Toronto, was rushed to hospital with what are described as life-threatening injuries.

Investigators are expected to be on the scene all day. No arrests have been made in the case and no suspects identified.

Police ask anyone with information about the incident to call 416-808-7400 or Crime Stoppers anonymously at 416-222-TIPS (8477).