A building at the corner of Panet St. and Ontario St. is crumbling.
Around 4:30 passersby called 9-1-1 to report the collapse of a wall.
Police closed Ontario St. between Visitation St. and Plessis St. while firefighters inspect the area and decide if the building must be demolished or not.
Neighbours said the building has been abandoned for nearly two years, ever since a fire broke out in April 2015.
The building was recently sold to a new owner.
It was also on the Montreal Fire Department's list of vacant and dangerous buildings.