A call to 911 about a heart attack has turned into Vancouver's fifth homicide of 2009.

Ambulance crews discovered the body of a 19-year-old man in the bathroom of a home in the 6400-block of Windsor Street of East Vancouver around 3:00 a.m. Friday while responding to a call about a possible cardiac arrest.

They immediately called for police, who secured the scene behind crime tape to search for clues.

Vancouver Police Const. Jana McGuinness says the man had been stabbed to death.

Several people in the home were taken to the police department for questioning but have been released. Police say they are still looking for at least one person -- and a weapon.