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.
In Delaware, an 83-year-old woman was found dead under a large branch close to her home.
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.
Video footage from New Jersey showed a roof being torn off a house as residents were told to stay indoors because of a threat of tornadoes.
About three million houses were without power by early Wednesday, utilities companies reported -- with New Jersey and New York worst hit by the outages.
Isaias quickly moved up the East Coast after slamming into the coast of North Carolina at hurricane strength.
"Isaias hit North Carolina head-on," Governor Cooper, adding that roads were being cleared and electricity restored.
"As clean-up continues, don't forget the pandemic is still with us. So help your neighbor, but do it safely by wearing your mask, keeping your distance and bringing your hand sanitizer."
New York authorities, ever-wary of the devastating damage caused by Superstorm Sandy in 2012, set up temporary flood barriers in Lower Manhattan in case of storm surge.
The orange flexible tubes known as "Tiger Dams" were put up in low-lying areas.
Public transport services were also briefly suspended including New York's famous Staten Island ferry.
But the rain turned out to be less heavy than feared.
"The storm has been much more of a wind event than flooding so far, thank God," New York mayor Bill de Blasio told local news station NY1.
- Tornado warnings -
At least 78 flights were canceled at New York's LaGuardia Airport. There were 55 cancelations at JFK.
Washington, Baltimore and other cities on or near the Atlantic coast experienced heavy rainfall.
The storm is expected to dissipate over north-eastern Canada late Wednesday or early Thursday.
It earlier dumped torrential rain on the Bahamas, felling trees and flooding streets, before emergency management officials on Sunday gave the all-clear.
At least one person died in Puerto Rico and the storm also lashed Haiti and the Dominican Republic.