Toronto police say that Tuesday's storms have led to reports of wires down, some fallen trees and flooding.

The storm that swept across much of southwestern Ontario brought between 15 to 20 millimetres of rain with locally heavier amounts, CBC meteorologist Michelle Leslie said. At Dufferin Street and Steeles Avenue West, the unofficial total was a whopping 58 millimetres.

The storm also caused extensive delays and some cancellations at Pearson International Airport. The temperature at the airport weather station dropped 10 C in just four hours.

Power was temporarily lost in parts of Scarborough and Markham, though it has since been restored.

Alliston, roughly 90 km north of Toronto, appears to be one of the worst-hit areas. Golf ball-sized hail was reported in the community, and winds in the 100 km/h range tore the roof off a truck repair shop.

In Georgetown, police are investigating if weather played a role in a crash that sent an SUV into a gym, leaving a person inside the building in critical condition.

There is still a risk of scattered thunderstorms over southern Ontario Tuesday night, Environment Canada said in a special weather statement. The storms may approach severe limits with large hail as the main threat, the agency said.