A rare tornado struck New York City on Saturday, blowing out the windows of at least one building, and a separate twister hit the Virginia suburbs of Washington, DC, as a line of fierce thunderstorms swept the region, knocking out power to thousands of homes.

There were no immediate reports of heavy damage or injuries from the storms, but the National Weather Service said a tornado watch remained in effect for parts of New York City, New Jersey and Connecticut.

A tornado warning, a higher level of alert, was posted on Saturday for much of northern Virginia and central Maryland, and two storms "capable of producing a tornado" struck near the Maryland suburbs of Langley Park and Bowie within 10 minutes of each other, the weather service said.

Area storms left more than 108,000 households and businesses in Virginia without power on Saturday, while over 60,000 electricity customers in the District of Columbia and the Maryland suburbs were hit by outages, local utilities reported.

As New York City was lashed with heavy rains and high winds, a tornado formed over the water near the Rockaway Peninsula of Queens, then moved inland over the beach-front neighborhood of Breezy Point, the weather service reported.

"We're confident in that it is a tornado," said meteorologist David Stark.

Caitlin Walsh, 24, who works at the Breezy Point Surf Club, said she and co-workers watched from their office as the twister "took everything into the air."

"We were all scared," she said. "The windows on the whole building broke, the lights went out, and the rain was pouring in. Everything was shaking. It was really crazy."

The weather service said winds in the tornado were moving at roughly 70 miles per hour (113 kph). Tornadoes are extremely rare in the largest and most densely populated US city.

The severe weather forced officials of the US Open tennis tournament to delay competition in the women's singles final at Flushing Meadows from Saturday evening until Sunday, the US Tennis Association said.

The New York Police Department said there were no immediate reports of injuries.

A spokesman for the New York Fire Department said there were reports of scattered damage throughout the city but the department had not yet confirmed the reports.

He said that in the borough of Brooklyn trees had been uprooted, power lines were down and part of the roof of a house had been ripped off. – Reuters