Police in Canada are warning of possible copycat attacks after three people died in a shootout in Montreal and the assailant’s lengthy manifesto, which called for “a new bloodletting”, was posted online by a far-right outlet.

The document contains many of the hallmark grievances of the “involuntary celibacy” – or “incel” – movement in addition racist and misogynistic conspiracy theories.

Fear gripped Quebec’s largest city on Monday after a man dressed in military camouflage and carrying a long gun was spotted moving around the Côte-des-Neige neighborhood. Shooting broke out and when police arrived, nearly 30 shots were heard. The shootout killed one officer and the gunman.

Video from witnesses appears to show the police accidentally killing a civilian during the firefight. Another injured officer suffered critical injuries but is expected to survive. Investigators from Quebec’s police watchdog, the bureau des enquêtes indépendantes (BEI) areinvestigating the deaths.

After the shooting, Canada’s federal police sent a bulletin to police agencies across the country warning the gunman’s manifesto is “allegedly encouraging citizens to shoot police officers”. The alert called on police to “exercise extreme caution and remain highly vigilant”.

The 104-page document, which was later posted in full by Rebel News, does not specifically mention targeting police, but blames feminism, liberalism and capitalism to explain the “situation of terrible loneliness, isolation, and social degradation” he believes men currently face.

The document also lists what the shooter claims are “valid potential class A targets”, including large investment banks, powerful politicians, “influential Zionists”, corporate executives in private healthcare, companies involved in environmental destruction, plastic surgeons and cryptocurrency speculators. The manifesto also mentions targeting “the headquarters of international pornography companies”.

It ends with the words: “Be unflinching, go forth, and KILL THEM ALL!”

Montreal police identified the slain officer as Mohamed Lamine Benredouane, 34, who had been with the force since 2021. The civilian, Michel Mizrahi, was identified as an Israeli citizen by Israel’s consulate in Montreal.

Footage from witnesses, viewed by the Guardian, showed an officer appearing to accidentally shoot Mizrahi. Quebec’s domestic security minister, Ian Lafrenière, said “there have been some rumors, there has been some information stating that the civilian was shot by a police officer. This is not the kind of information that we can share at this moment,” adding the watchdog was investigating.

The fatal shooting marks the third time a Canadian police officer has been killed while on duty this month. Two Royal Canadian Mounted Police officers were also shot and wounded Monday in the province of Saskatchewan during a property dispute.

In recent years, Canada has witnessed a string of attacks apparently inspired by extreme misogyinst incel ideology.

In 2018, the driver of a van killed 10 and injured more than a dozen others in Toronto. The perpetrator of a 2020 machete attack at a Toronto spa in which one woman was killed and another seriously injured was also motivated by the ideology and the case marked the first incel-related incident in Canada to be deemed an act of terrorism by the courts.

The country is also still grappling with the fallout of the 1989 attack on Montreal’s Polytechnique engineering school, where a young man walked into building with a semiautomatic rifle, killing 14 women and injuring 14 others (including four men). He then killed himself.

Christine Fréchette, Quebec’s premier, told reporters she was “deeply shocked and saddened” by Monday’s attack and ordered the Quebec flag to fly at half mast.

Mark Carney, Canada’s prime minister, said that he was “horrified” when he learned of the shooting. “My thoughts are with the victims, their loved ones, the first responders, and the entire community of Côte‑des‑Neiges,” he said in a statement posted to social media.

The city’s mayor, Soraya Martinez Ferrada, said she extended her “deepest condolences to the family, friends, and colleagues of the police officer who died in the line of duty”.