"The damage was not substantial but it was widespread," said Hydro One spokesperson Al Manchee, adding that power should be restored quickly.
Hydro One has 1.2 million customers across Ontario.
York Region was one of the hardest-hit areas, especially in the area of Yonge St. and Highway 7. PowerStream Hydro, which serves 230,000 customers in York Region, said that up to 20,000 customers were without power after the storm.
The storm caused damage throughout Toronto and surrounding communities. On Fee Ave. in Vaughan, a 10-metre pine tree was knocked down across a residential lawn, while in Toronto, a large tree was knocked into a house in the Pape Ave. and Queen St. E. area.
Although there were reports of tornado sightings, forecasters say there was no evidence that a funnel cloud had actually formed.
The storm hit just before 5 p.m., causing dozens of traffic jams during rush hour.
The powerful winds knocked down hydro and telephone poles on stretches of roads through York Region, affecting Keele St. north of Highway 7 and along Bathurst and Yonge Sts., south of Highway 7.
York transit buses were diverted off Yonge St. after seven hydro poles were toppled.
Trees and downed lines were removed overnight from Keele, Bathurst and Yonge streets., as well as Bayview Ave. in Vaughan. However, as of mid-morning, lanes were still closed on Yonge St. south of Highway 7 as hydro poles were cleared away.
There was no access to Langstaff Rd. from Yonge St. in Thornhill at one point, causing delays for commuters attempting to access GO trains.
A spokesperson for PowerStream Hydro in York Region said the outages were the worst the region has experienced since the blackout in 2003, with 60 hydro poles either snapped or leaning in the aftermath of the storm.
The hardest-hit areas in York Region were the Yonge St. and Royal Orchard Blvd. area and the Bathurst St. and Highway 407 area, both in Thornhill.
At the height of the storm, some areas in the region recorded nine millimetres of rain in only 10 minutes.