TORONTO - About 40,000 Hydro One customers remained without power Friday afternoon following devastating storms that hit cottage country earlier in the week.

A Hydro One spokesperson said crews have restored power to more than 110,000 customers in southern Ontario following this week's severe weather system.

The majority of customers are expected to have power restored over the next 24-hours, Hydro One said.

Myles D'Arcey, Hydro One's customer operations senior vice-president, said that the work that lies ahead will be the hardest.

"We are now entering into the most difficult stage of our restoration effort," D'Arcey said in a release.

"As power is restored in one area, we will concentrate crews in areas where help is needed until everyone is back on."

Hydro One currently has 1,300 employees working across the province on restoration efforts.

Wednesday's severe thunderstorms knocked out power to more than 150,000 customers and toppled hundreds of hydro poles across southern Ontario.

"The extent of the damage to our system is significant," D'Arcey said.

For residents of the affected areas, chainsaws were the order of the day to clean up fallen trees and other damage.

The storm forced the closure of schools in several communities, and dozens of school bus runs were cancelled because of downed trees and power lines.

Municipal officials in Tweed Township, northeast of Belleville, called on rural residents to drive the back roads only if necessary.

In Ottawa, the Bob McQuarrie Recreation Complex was flooded, but city officials said they had no reports of homes being flooded.

Ottawa's forestry services department responded to about 80 calls for fallen trees and branches across the city.

Lightning strikes spark seven fires in Vaughan

In Vaughan, north of Toronto, the fire department had 14 calls for lightning strikes, seven of them resulting in house fires.

The worst of them destroyed the roof of a house, but there were no injuries.

Environment Canada has been investigating reports of suspected tornadoes spawned by Wednesday's weather.

Officials said Thursday that preliminary data indicated that downbursts, not tornadoes, were responsible for damage in places such as Hamilton and Guelph.