A severe weather system that hammered southern Ontario on Tuesday with heavy rain, thunder and wind left more than 27,000 people without power and caused significant damage in some areas.

Environment Canada issued a severe thunderstorm warning for most of southern Ontario ahead of an intense band of weather that had the potential to bring 100 km/h winds, large hail and lightning.

Hydro One said following the storm, more than 27,000 people were left without power.

"Crews have been dispatched and will restore power as quickly and safely as possible," Hydro One said.

Toronto Hydro also dispatched crews following outages in the city but said the majority of power was restored around 9 p.m.

Meanwhile, video posted online appears to show a possible tornado near Lucknow, which is just south of Port Elgin. There are reports of widespread damage in the area.

The potential tornado has not been confirmed by Enviorment Canada. 

Saugeen Shores Police Service tweeted Tuesday night they had experienced a "significant weather event" and that many power lines are down in the area.

The severe thunderstorm warning for Toronto ended just before 8 p.m.

Toronto Pearson also warned travellers about the storm on Tuesday, saying that the weather system may cause delays to flights.