Isaias causes its first casualty in North Carolina as it ravages the Northeast and knocks out power to hundreds of thousands and threatens to trigger tornadoes.
Tropical Storm Isaias has pummelled Virginia on its way toward Washington and other cities of the US Northeast, and killed at least one person after a tornado it spawned obliterated a mobile home park in North Carolina.
The fast-moving storm knocked out power to hundreds of thousands and threatened to trigger more tornadoes on Tuesday, with the centre of the storm about 160 km south of Washington as of 8 a.m. Eastern time 1200 GMT, the National Hurricane Center said.
Two people died when Isaias spun off a tornado that struck a North Carolina mobile home park. Authorities said two others were killed by falling trees toppled by the storm in Maryland and New York City.
It was moving toward the north at 54 kph, packing maximum sustained winds of 110 kph.
A tropical storm warning remained in effect all the way to Maine, with major cities such as Washington, Philadelphia and New York in the potential path.
Tornadoes were possible from Virginia to New Jersey through midday and from New York to New England in the afternoon and evening, the hurricane centre said.
The Washington area was experiencing heavy rains as Isaias blew through on Tuesday morning, with authorities warning of flash floods, and some low-lying roads closed due to flooding.
More than 600,000 homes and businesses in North Carolina and Virginia were without power, according to electric companies.
The storm had regained hurricane strength late on Monday just before making landfall in southern North Carolina shortly before midnight.
It was downgraded to a tropical storm while flooding homes and streets in North Carolina, killing one person and injuring several others in a mobile home park, officials told local media.
News pictures showed a field of debris where the mobile home park once stood in Bertie County in the northeastern corner of North Carolina.
Three or four people were missing, and at least two of them were children, WITN television reported, citing Sheriff John Holley. Some 10 to 12 mobile homes were destroyed and vehicles were tossed atop each other, the sheriff said.