Montreal police are investigating after a father and his two children, aged seven and five, were found dead in a home in the borough of Mercier-Hochelaga-Maisonneuve.

The mother of the children found the bodies after returning home from work Tuesday evening.

Montreal police are investigating the possibility the man, 40, killed his two children before taking his own life.

Police set up a perimeter around the home early Wednesday could be seen going in and out of the small brick-faced home. The major crimes unit is at the scene.

Investigators will also be speaking with family and friends of the victims as well as neighbours to better understand the circumstances surrounding the deaths, said Montreal police spokesperson Const. Manuel Couture.

"The investigators will be there for almost all day today," he said.

"It's going to be a long investigation because it's a complex scene inside the house."

Police set up a perimeter around the home late Tuesday. (Alain Béland/Radio-Canada)

Police were called to the small, two-storey brick home on a grassy corner lot at Curatteau Street and Pierre-de-Coubertin Avenue, just east of Highway 25, at around 9 p.m. Tuesday.

"When police arrived on the scene, they located the body of a 40-year-old man and the bodies of two children," Couture said. "The death of the three people was confirmed at the scene."

The body of one of the children was found in the basement and the other on the first floor. The man was found dead in an upstairs bedroom.

Radio-Canada has learned that the man and the mother of the two children were in the midst of a separation.

Couture said all scenarios are being investigated.

Any time officers respond to violent incidents, it is emotionally difficult, Couture said, but it is particularly challenging when there are children involved. Professional services have been made available to those officers who were first on the scene.

Neighbours shocked by news

The family's small home faces a grey wall that serves as a sound-barrier to block the noise from Highway 25. It's on the western edge of a neighbourhood lined with similar single-family homes, small apartment blocks and quiet, kid-friendly streets.

The treed neighbourhood where the incident took place is lined with modest single-family homes and small apartment blocks. (Google Earth)

Isabelle Rousseau lives nearby. She was in tears this morning, shocked to learn of what happened on the street, even though she didn't know the family directly.

She saw them often when she walked her dog in the neighbourhood, and she never noticed any signs of problems, she said.

"It hurts my heart to know people living so close were in distress," Rousseau told CBC News, her voice shaking with emotion.

"When help is needed, get the help needed and don't do what was done here yesterday evening."

She left flowers on the family's front porch, placing them next to a growing collection of stuffed animals and handwritten notes left by others who have heard about the deaths.

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