TORONTO -- A massive thunderstorm has torn through parts of southern Ontario, leading to tornado warnings and reports of a funnel cloud spotted in cottage country.

Environment Canada had issued a tornado warning for much of cottage country as heavy winds snapped trees and sent residents running for shelter from lashing rain.

The weather service says there were unconfirmed reports of a funnel cloud near Barrie during the height of the region's tornado warning, which was lifted later in the afternoon.

Tens of thousands of houses had their power knocked out, with more than 35,000 Hydro One customers without power in the Midland-Barrie-Orillia area.

Environment Canada says the thunderstorm that emerged earlier in the afternoon was tracking east, though there are no confirmed reports of any tornadoes.

The southern Ottawa area had been hit with a tornado warning, but that was lifted just after 4:30 p.m.

Severe thunderstorm warnings remain in place for much of southern Ontario.

Provincial police in Orillia and the surrounding area say they have been slammed with emergency calls.

Staff Sgt. Sharron Brown says they have received reports of property damage caused by intense winds.

"We've heard of trees down on top of a vehicle, trees down across roadways blocking traffic," she said.

"Right now the priority is to respond to the calls for service," she said.