Police say the pedestrian was hit around 6:20 a.m. on Barclay Avenue near the corner of Légaré Street.
Montreal police Const. Jean-Pierre Brabant says the man suffered severe head injuries.
As of 10:45 a.m., his injuries were considered life-threatening.
"That’s what’s tricky with his age. We’re trying to get a scan to know if he’s getting better, but for now we’re waiting for the result," said Jean-Pierre Brabant.
Brabant said a 59-year-old woman has been arrested and is being questioned by police.
They have not yet laid charges.
"For now it is considered a hit-and-run with a vehicle that came into a collision that did not stay on site," said Brabant.
Investigators are analysing the crime scene and speaking with drivers who may have witnessed the collision.
"It appears the pedestrian was trying to cross the street and that the vehicle came into the collision with the pedestrian," said Brabant
Brabant said Barclay Street has been closed westbound and Lavoie street northbound.
He said officers are on site to redirect traffic.