NEW YORK/WASHINGTON –– New York awoke in shock Tuesday to the devastation of superstorm Sandy, which left at least 10 dead in the city and threatened to leave days of chaos in its wake.

Firefighters battled blazes and carried out rescues in flooded houses a day after the storm set off an explosion at a power station, while scores of homes were destroyed by fire or the record 13.9 foot (4.2 metre) storm surge, officials said.

Subway trains and buses remained suspended for a third day and hundreds of thousands of homes face up to a week without electricity, the power company warned.

Runways at New York's three main airports were flooded extending the international air chaos caused by the storm, though John F. Kennedy airport could reopen Wednesday, officials said. The New York stock exchange was closed for a second day.

Ten storm deaths in the city were reported by Mayor Michael Bloomberg, who warned the toll could rise.

One man was crushed by a tree in Queens. Bloomberg said another person stepped in a puddle in which there was an electric wire and two people were found drowned in a flooded house.

New York state governor Andrew Cuomo said that New York police and national guard troops "saved hundreds of lives yesterday".

Firefighters battled 23 serious fires some of which continued Tuesday, Bloomberg told a press conference. He said 80 homes were destroyed.

Smoke lingered over many streets after a huge fire tore through 50 homes in the Breezy Point district of Queens. Firemen in boats rescued about 25 people trapped by fire. The homes were left a tangled mess of wood and metal.

Breezy Point is near Rockaway Beach, where firemen rescued several people trapped in their homes by waves which tore into the streets. Upturned cars were left strewn across roads.

A spectacular explosion at a Manhattan electricity sub-station at the peak of the storm cut power to 193,000 homes on the island.

About 300,000 other homes in New York lost electricity as Sandy tore down trees and flooded power transmission facilities.

"Don't be surprised if it takes a week" to get power back, warned Con Edison electricity company spokesman Alfonso Quiroz.

Many roads remained blocked by trees, and road tunnels were inundated by floodwaters that slowly receded after the city was battered. Bridges off Manhattan were only open to emergency services.

Some subway stations had water above platform level and it was expected to be several days before trains were fully operational again.

Metropolitan Transportation Authority (MTA) president Joseph Lhota said the New York subway "has never faced a disaster as devastating as what we experienced last night."

On Tuesday, President Barack Obama expressed sadness over deaths from superstorm Sandy and directed federal responders not to let up in their help to disaster areas after a top-level briefing Tuesday.

Obama held a video-teleconference with top officials in the Situation Room of the White House on the latest developments associated with Sandy, which roared ashore Monday with hurricane-force winds, causing serious floods and wind damage.

"During the briefing, the president expressed his concern for those impacted by the storm, as well as the heroic first responders who are selflessly putting themselves in harm's way to protect members of their communities," a White House statement said.

"He also noted his sadness over the loss of life associated with the storm so far." At least 25 people have so far died in the storm in the mainland United States and Canada.

"The president told his team that their top priority is to make sure all available resources are being provided to state and local responders as quickly as possible and directed them to identify and resolve any potential bottlenecks or shortfalls should they arise."

Obama's meeting included Vice President Joe Biden, Homeland Security Secretary Napolitano, Craig Fugate, the chief of the Federal Emergency Management Agency and the secretaries of energy, transportation and defense.

The president also told his top aides that he wanted the government to go beyond lifesaving activities to support state and local efforts to restore power, following widespread outages.