Police said water was pouring onto Sherbrooke Street between Peel and University streets, complicating the rush-hour commute, the Canadian Broadcasting Corp. reported.
University of McGill employees were sent a memo warning them of "severe flooding on the downtown campus that originated near the McTavish reservoir." The note said several buildings had flooded, the CBC said.
The (Montreal) Gazette reported the water main break occurred near the McTavish Reservoir, an underground reservoir that holds 37 million gallons of water.
The newspaper said McGill administrators had issued a statement urging anyone in the university's basement levels to evacuate to higher ground.