Police got a call Tuesday around 12 p.m. about an attack in Côte Saint-Luc. Officers found the woman on the ground in the parking lot of the building on Cavendish Boulevard, near Louis-Pasteur Road.
Montreal police spokesman Manuel Couture said the victim was assaulted with what appeared to be a blunt object.
The woman suffered major wounds to her upper body.
Police called the incident "an armed robbery gone wrong."
Investigators do not have any suspects in the case and have not made an arrest.