Photo: The Canadian Press

Tens of thousands of Ontario residents are facing another day without power as restoration efforts continue following a vicious weekend storm.

Environment Canada said a derecho – a rare widespread windstorm associated with a line of thunderstorms – developed near Sarnia, Ont., on Saturday and moved northeastward across the province.

Hydro One says about 68,800 customers are still in the dark, with those in the Bancroft, Perth and Tweed regions expected to be without power for several days.

Hydro Ottawa says some 45,000 customers are still without power but most are expected to have service restored by Friday.

At least 10 people died after Saturday’s storm, which toppled trees, downed power lines and damaged property.

Peterborough is the latest community in Ontario to declare a state of emergency after the storm hit on Saturday. Residents in the area are being asked to avoid unnecessary travel to make it easier for emergency services to respond to calls for assistance with downed trees and power lines.

The communities of Uxbridge, Ont., east of Toronto, as well as the Township of Greater Madawaska, and Clarence-Rockland also declared states of emergency.