11/10/2014 07:36 EST | Updated 01/10/2015 05:59 EST

Halloween attack on Vancouver teen puzzles police

Police in Vancouver are seeking tips on an attack that left a 16-year-old boy bleeding in South Vancouver the morning after Halloween, with what appeared to be a stab wound and a collapsed lung.

The Vancouver Police Department says that what is known is that the 16-year-old left a house party the night before, and was last seen at around 11 p.m. PT in the south lane of E. 60th Avenue near Inverness Street.

Seven hours later, at around 6 a.m. PT, the teen was shirtless, shoeless and bleeding when he knocked on the door of a house on E. 60th Avenue near Ross Street, asking for help.

"He was taken to hospital where he was diagnosed as having suffered a possible stab wound to the chest, a collapsed lung and scrapes and bruises to his face," the department said in a written statement.

Sgt. Randy Fincham said the teenager's cellphone, wallet and jewelry was missing.

Fincham said someone knows what happened to the teen between 11 p.m. on Halloween and 6 a.m. on Nov. 1, and police are asking anyone with information to come forward.

"There are pieces to this puzzle that are still missing," Fincham said.

The 16-year-old is South Asian and has short black hair and a moustache. He was wearing a black toque and a silver chain around his neck that night.

The Vancouver Police Department's major crime section can be reached at 604-717-2541, and CrimeStoppers can be reached at 1-800-222-8477.