NEW YORK: Tropical storm Isaias left at least five people dead as it pounded the US eastern seaboard with driving winds and heavy rain, leaving millions without power, before moving across Canada on Wednesday.

Isaias was downgraded to a post-tropical cyclone late Tuesday as as it streaked across the border into south-eastern Canada after wreaking havoc across several US states.

A tornado ripped through a mobile home park in North Carolina killing two people while two more died as trees fell on their cars - one in New York and one in Maryland.

Forecasters warned of heavy rain across Quebec and wind gusts up to 50 miles (80 kilometers) per hour after the storm littered streets with debris and forced the cancellation of scores of flights in the US.

About three million houses were without power by early Wednesday, utilities companies reported - with New Jersey and New York worst hit by the outages.

At least 78 flights were canceled at New York's LaGuardia Airport. There were 55 cancelations at JFK.