NEW YORK - A loud explosion shook the Chelsea neighborhood of Manhattan on Saturday night, prompting New York City police and fire department personnel to swarm the area, a Reuters witness said. At least 15 reportedly injured in New York City Blast,said media.

At least three people were seen being taken away from the apparent scene of the blast in ambulances, but the severity of their injuries was not immediately clear. A car seen driving through the area had its rear window blown out.

Police and fire representatives said they were investigating reports of an explosion.

New York City Police issued a bulletin advising motorists in the area that they should "expect extensive traffic delays and emergency personnel in the area of 23rd Street and 7th Avenue" due to police activity there and asking the public to avoid the area.

The blast, according to a Reuters witness, occurred on 23rd Street, a major east-west thoroughfare in the fashionable downtown neighborhood of Chelsea.

Hundreds of people were seen fleeing down the block on a cool early autumn evening, as police cordoned off the area.