Toronto police are investigating the second murder in less than 12 hours after a man was found dead early Friday morning following a fight. The death marks the city's fourth homicide in five days.

Officers responded to a call for an altercation at an apartment building at 65 Greenbrae Circuit, near Markham and Lawrence Avenue East, at about 2:30 a.m.

They found an unconscious man with serious head injuries. The victim was taken to hospital, where he later died.

The man's identity has not been released because his next of kin has not yet been notified.

An autopsy is scheduled for Saturday to determine the exact cause of death. He is the city's 15th homicide of the year.

Just 11 hours earlier, police were called to a shooting outside an Etobicoke adult learning centre that left an 18-year-old student dead.

The man was shot in the head outside Burnhamthorpe Collegiate at about 3:30 p.m.

Police said the killing was "intentional," but refused to identify the targeted victim.

Investigators are looking for two or three suspects in a dark "high-end" four-door sedan. The vehicle's rear passenger side window was shot out, police said.

On Tuesday, firefighters found the lifeless body of 29-year-old Tito Benjamin in his Cabbagetown apartment during a medical call in his building.

Police said Benjamin was fatally shot, and the motive may have been robbery.

A day earlier, 20-year-old Allen Benn was stabbed to death outside an apartment in the Jane and Finch area.

Police are looking for as many as six men who are believed to be involved in the killing.

Anyone with information about these cases is asked to contact the Homicide Squad at 416-808-7400 or Crime Stoppers anonymously at 416-222-TIPS (8477). Information can also be left online at www.222tips.com.