Police are investigating after a man was found dead in a southwest back alley following a fight. (CBC)

Calgary homicide detectives are scouring the scene and searching a black Cadiliac left behind after a back alley brawl turned deadly in the southwest community of Rosscarrock.

Officers found a man's body in the alley behind a house in the 900 block of 43rd Street S.W. just after 7 p.m. Wednesday night. They were responding to a call about a fight in the lane.

"We did have a group of people that were fighting prior to police arriving. The only person left in the alley was our victim," said Duty Insp. Michael Watterston.

Police said the dead man — believed to be in his 40s — was involved in an altercation wtih three young men who ran away. Two of them then fled in a vehicle, police said.

Officers found weapons at the scene, and investigators were interviewing several witnesses. An autopsy was completed Thursday but police did not reveal the cause of death or the man's identity.

'There was somebody lying on the ground and then he saw two kids high-tailing it up the alley.'—Gordon Brown, area resident

"We believe the combatants knew each other and we believe this incident is drug related," said acting Staff Sgt. Rick Tuza.

Gordon Brown, who lives in the area, heard about the attack from his daughter's boyfriend, who was nearby when the altercation happened.

"He just saw a vehicle there. The doors were open, the lights were on and there was somebody lying on the ground and then he saw two kids high-tailing it up the alley," he said.

"He went and followed them and then some van came and picked them up and took off so he took pictures of the van… He lost them from there," Brown said, adding that he believed those pictures are now in the hands of police.

"It's scary like I would never consider walking by myself towards the evening ever again in this neighbourhood. I mean hell, I might even move out of this neighborhood if this is what it's going to be like," said Tyler Bryk, who lives a few houses away from the scene. "I lived in Varsity most of my life and I've never seen anything like this."