The other tornado is suspected to have hit an area with no built infrastructure in Salaberry-de-Valleyfield, Que., also causing no damage, she said.
In Sorel-Tracy, east of Montreal, there were reports that powerful winds had caused heavy damage.
The alerts in Quebec came after a tornado touched down in the Ottawa neighbourhood of Barrhaven, where about 125 homes were damaged but there were no reports of injuries.
The storm system was accompanied by high winds and torrential rains that led to flooding of some streets and highways in Montreal. The Décarie Expressway was closed in both directions at the height of the evening rush hour because of water accumulation. It reopened about an hour later.
At Montreal’s Trudeau Airport, many flights were delayed or cancelled, and wind gusts up to 98 km/h were recorded.
Mayor Valérie Plante wrote on Twitter late Thursday that “despite the power of the storm, no major damage has been done to municipal infrastructures at this point.”