At least four people have been killed as a massive storm barrelled along the US east cost, bringing power outages, flooding and flight delays.

A woman died in floodwaters outside Charleston, South Carolina, and three men in north-eastern states were killed as the storm moved towards Canada.

Millions of East Coast residents were on flood watch and more than 600,000 were without power on Tuesday morning.

Lingering into Tuesday, the storm was expected to snarl up holiday travel.

The weather brought widespread heavy rain that led to river flooding and flash flooding, the US National Weather Service (NWS) said. Some areas were "experiencing road washouts". Wind gusts reached nearly 70 mph (113km/h) along the southern New England shoreline.

The first storm-related death was confirmed in Mount Pleasant, South Carolina. Nancy Morrow, 72, was killed after she got stuck in a vehicle submerged in water, officials said. Officers jumped in the water to try to save her.

In Hanover, Massachusetts, on Monday an 89-year-old man, Robert Horky, died after strong winds knocked a tree on to his trailer, causing severe head trauma, local officials said.

A 40-year-old man, whom police have not yet named, died in Windham, Maine. A tree fell on him while he was trying to clean debris from his roof, authorities said.

And in Pennsylvania, 73-year-old Allan "Ray " Nolt died on Monday morning after his vehicle was submerged in high water, according to coroner's office in Lancaster County.

Heavy winds and rain made for dangerous travel conditions, leading to more than 4,900 delayed and 500 cancelled flights travelling to or in the US on Monday, according to FlightAware. The worst-affected airports were in the Boston and New York areas.

Schools across the New England region have also been forced to cancel or delay classes because of road conditions.

Drier weather is expected in the coming days, according to the NWS, allowing some of the flooding to recede.

In Boston, Massachusetts, winds were as strong as 50mph (80 km/h), according to the local NWS, and flooding remained a "significant concern" as of early Tuesday morning.

Dozens of people stranded in floodwaters were in need of rescue near the waterfront area of Georgetown, South Carolina, where more than 9in (22cm) of rain fell, officials said.

In total nearly 60 million people from Virginia to Maine were under a flood watch.

The weather comes nearly a year after a major winter storm in the US caused travel chaos during the holiday travel season. (BBC)

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