A break in a major underground water main near Montreal's Jacques Cartier Bridge sent water gushing down streets and inside homes on Friday morning, forcing the evacuation of nearby buildings.

Montreal Mayor Valérie Plante said many residents east of downtown woke up around 6 a.m. to firefighters urging them to vacate their homes because of flooding risks from the "geyser" that erupted at the corner of René-Lévesque Boulevard and de Lorimier Avenue.

Images broadcast by media showed water gushing from the intersection in the densely populated neighbourhood near the bridge, and witnesses said that at its peak it was shooting 10 metres high.

"Even if the water is receding, we are asking people to let repair crews do their work; don't cross the danger tape," Plante told reporters near the site, adding that work to fix the leak will likely take "several hours."

The source of the flooding is a pipe more than two metres in diameter installed in 1985, said officials, who explained the asphalt and concrete above the broken section of pipe will need to be excavated before they know how serious the problem is.

But officials said that thanks to redundancies in the city's network of 4,000 kilometres of pipes, there are no safety issues with drinking water in the flooded district. Every sector of the city is fed with at least two water mains, they said, allowing crews to turn one off and maintain drinking water for the area.

By 10:30 a.m. water had begun receding in the district, but there was still an impressive stream flowing down streets in the neighbourhood.

Martin Guilbault, division chief of the Montreal fire department, said people should stay away from the flooded area until authorities give the green light to return.

"Just because there is less water doesn't mean the work is done," he said, explaining that parts of streets could be damaged and give way from all the water that poured over them.

Fire officials didn't give a precise number of people evacuated, telling reporters that crews visited all the buildings affected and ensured everyone was safe. They said crews still need to evaluate the danger before residents can return home.

Quebec's hydro utility cut power to the affected area as a precaution, leaving about 14,000 clients without electricity.