A 16-year-old boy was stabbed in the upper body on Lake Road, shortly after 10 p.m.
The victim made his way to a friend's house and was later taken to hospital.
Authorities are looking for two suspects, believed to be between 18 and 20 years old.
Sgt. Yannick Ouimet said the investigation is proving to be difficult.
"The victim is not cooperating with police but his friends are not either," he said. "It's very difficult to know what happened yesterday."
Two brothers stabbed
Police are also investigating a double stabbing that took place in Villeray around 1:25 a.m. on Sunday.
Police believe two brothers, aged 28 and 30, stabbed each other in an apartment on Faillon Street.
Both were sent to hospital with head injuries but authorities expect them to recover.
Investigators have yet to find a motive.