Montreal police Const. Julien Lévesque said a 911 call was received at about 9:20 a.m. for a person in need at an address on Bélanger Street, in the city’s Rosemont neighbourhood.
The suspect was arrested outside the apartment building and will be questioned by investigators.
Authorities have barricaded off the street consisting of low-rise apartment buildings, across the street from the Montreal Heart Institute. An ambulance with lights flashing remained on scene, along with a police mobile command post and a large number of police vehicles.
A spokesperson for the Urgences-Santé ambulance service said it was called to the scene, but no transports were needed.
Quebec Premier François Legault and Mayor Valérie Plante were quick to offer condolences via social media.
Vincent Marissal, the Québec solidaire member who represents Rosemont in the legislature, said he has reached out to the province’s public security minister to get more information about what happened.