A deadly shootout in Montreal left a police officer, a civilian, and the gunman dead after a heavily armed attacker opened fire in the Côte-des-Neiges neighborhood.

Authorities say the suspect left behind a 104-page manifesto containing incel-related grievances, racist and misogynistic conspiracy theories, and calls for violence.

Canadian police have warned of potential copycat attacks and urged officers nationwide to remain highly vigilant.

Investigators are examining whether the civilian was accidentally killed by police during the exchange of gunfire, The Guardian has reported.

The attack has renewed concerns about violent extremist ideologies in Canada, particularly those linked to the incel movement, which has been connected to several deadly attacks in recent years.