Police say a 16-year-old boy was seriously injured following an "assault" outside a high school in Montreal North on Monday.

Police say the incident happened around 4:20 p.m. as the victim left the École Calixa Lavallée High School on Pelletier Avenue during a conflict with a group of people.

The teen was conscious en route to hospital with a serious upper-body injury from a "blunt" object, according to Veronique Dubuc, a spokesperson for the Montreal police service. The teen was sent to hospital in critical condition, but his condition has since improved and police no longer fear for his life.

Police have not made any arrests but are looking for suspects who fled the scene after the attack.

The investigation is ongoing.