Thousands of people remain without power in west Quebec and eastern Ontario this morning after thunderstorms swept through the region Monday.

The storms caused "significant damage" in the Outaouais, according to a notice posted on Hydro Quebec's website.

About 8,400 customers were without power as of 6 a.m. Tuesday, the hydro corporation reported.

By 7:40 a.m. that number had dropped to about 6,000, and by 9:30 a.m. it had climbed back up to about 7,000.

In an interview Tuesday morning, Hydro Quebec spokesperson Lynn St-Laurent said about 50 crews have been working to restore power to the region.

"Some of our teams have reported electricity poles that were brought down sometimes in a cascade, either four or five in a row," she said.

In Hydro One's eastern Ontario territory, about 2,000 customers in the Bancroft area remained without power as of 6 a.m. About 360 were without power in Cobden, 138 were without power in Tweed, 70 were without power in Kingston, and less than 20 were without power in Arnprior.

As for Hydro Ottawa, no customers were without power as of 6 a.m.

At the height of the storm, about 3,800 customers in the Nepean area were without power, in addition to about 800 customers in the west end and 300 in Cumberland and Osgoode.