A midday shooting in Montreal left three people dead on Monday, including a police officer, a civilian, and the suspected gunman, in an outbreak of violence that shocked a city where such attacks remain rare and quickly triggered a massive police response and a widening investigation into motive.

The attack unfolded in the Cote-des-Neiges district of Montreal after emergency calls reported a man firing from inside a building near a busy commercial stretch that includes shops, restaurants, and religious institutions.

Police said officers arrived shortly after 11:30 a.m. local time and immediately came under fire from a suspect armed with a long gun and dressed in military-style clothing, leading to an exchange of gunfire on the street and inside the building.

Authorities confirmed that a male police officer was killed during the initial exchange. A second officer, a woman, was seriously wounded but is expected to survive. A civilian was also killed during the chaos, though officials said it remains unclear who fired the fatal shot. The suspected gunman was later killed at the scene.

Montreal police Chief Fady Dagher described the episode as “a tragedy, a nightmare,” noting the rarity of a fatal attack on law enforcement in the city. Officials said it was the first killing of a Montreal officer in the line of duty in 24 years, underscoring the scale of the shock within the police force and across the city.