The extreme cold caused a water main break on Montreal's Plateau Mont Royal this morning, flooding St-Denis Street at St-Joseph Boulevard.

With temperature hovering at around -21 degrees, water gushed down St-Denis Street, spreading across several traffic lanes.

Police have closed St-Denis Street between Laurier and Mont Royal avenues, and St-Joseph Boulevard between Henri-Julien Avenue and Berri Street.

Montreal public works employees are on the scene trying to fix the break.