More than 300,000 Canadians faced power outages in parts of Ontario on Sunday as an ice storm pummeled the region over the weekend, according to electricity provider Hydro One.

Environment Canada issued winter storm warnings for freezing rain in Ottawa, parts of Quebec and Ontario, with the risk of snow mixed with or transitioning to ice pellets expected to continue until Monday morning in some regions.

“Outages are largely being caused by tree limbs and branches being weighed down from the accumulation of freezing rain,” Hydro One said on its website, noting there is also the risk of flooding for central Ontario.

More than 300,000 customers were affected as of Sunday afternoon, according to the website, with power expected to be restored on 1 April.

Utilities provider Alectra said there were about 35,000 customers without power, primarily in Barrie, a town north of Toronto. “Progress has been slow due to the ice on the lines, but all available resources have been deployed,” it said on Sunday.

The city of Orillia in Ontario declared a state of emergency due to the storm as prolonged freezing rain continues to cause widespread power outages, hazardous road conditions, downed trees and hydro lines, and damage to public and private infrastructure.

“This is a very serious situation with hazardous road conditions, downed trees and hydro lines, and damage to public and private infrastructure,” the city said on its website.

Several residents across Ontario said on social media that roads were closed due to uprooted trees and they had heard crashing tress since the storm began.