The death toll from powerful storms that lashed eastern Canada over the weekend has risen to at least eight, authorities said Sunday.

Police in the province of Ontario announced on CTVNews the deaths of seven people, killed Saturday by falling trees and branches.  

The eighth victim was a woman who drowned when her boat capsized in the Ottawa River, near Gatineau, a Quebec suburb of the federal capital Ottawa.

Strong winds, with gusts of more than 140 kilometers (87 miles) per hour, battered eastern Canada on Saturday, the national weather service said, adding that the storm was a rare phenomenon called "derecho".

"This storm was almost about 1,000 kilometers" long, Environment Canada Senior Climatologist David Phillips told local station CFRA on Sunday.

"That's what a derecho is, it's a long line of very active thunderstorms or microburst kind of situations," he said.

"Nothing can deter it. It just marches along."

Some 900,000 homes lost electricity Saturday night, with hundreds of thousands of households still in the dark by Sunday evening, local energy providers Hydro One and Hydro-Quebec said on Twitter, as they worked to restore power.

Roads remained strewn with branches and debris, with authorities saying it would take several days to clear.