A man in his 20s has been arrested after stabbing a woman and assaulting three other people in St. Leonard early Thursday.

Police say around 4:30 a.m., several calls were placed to 911 about a woman who was seriously injured in an apartment on Cannes St. near Jean Talon St. E.

The suspect allegedly stabbed the 42-year-old woman in the upper body. She was transported to hospital and is in critical condition.

There were two witnesses to the alleged attack at the apartment – a woman in her 20s and a young child, police say.

The man, the alleged victim and the witnesses know each other, but police say they are trying to determine their exact relationship.

The suspect then fled on foot and began attacking people on the street, police say.

He allegedly assaulted a man picking up garbage, an STM bus driver and a pedestrian.

The first man was brought to hospital and treated for a concussion.

Police were able to retrace his path using the canine unit.

Police found the suspect in an apartment less than a kilometre away from where he had stabbed the woman, on Provencher Blvd., near Jean Talon and arrested him.

He had forced his way into the home, police say.

The elderly couple who lived in the apartment was treated for shock.

Investigators are at the scene in St. Leonard, and are trying to determine, among other things, what prompted the man to stab the woman.