An explosion in New York has left several people injured and sent hundreds fleeing from the site.

An explosion in Manhattan, New York has injured at least 26 people, with police and fightfighters responding now.

The fire department was deployed to a building at 135 West 23rd Street near Sixth Avenue, in Chelsea, around 8.30pm Saturday, New York time (10.30am Sunday AEST).

The New York Post has reported at least 26 people suffered minor injuries from what is believed to have been an explosive device.

The explosion happened outside the Associated Blind Housing facility, which provides housing, training and other services for the blind.

The Daily Mail has reported a car was seen driving through the area had its rear window blown out.

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. It was reported that part of the building may have collapsed.

Hundreds of people were seen fleeing down the block.

Many social media users have posted photos of the aftermath and injured victims.

The explosion in the Chelsea neighborhood comes just hours after pipe bomb exploded along a route of a charity run in New Jersey, the Daily Mail has reported.

Spectators had gathered just a few blocks from the blast in Jersey Shore town on Saturday afternoon.

The pipe bomb near D Street exploded about 9.30am, but no injuries were reported but bomb-sniffing dogs have continued to look for more bombs in the area.