AKIPRESS.COM - At least 29 people have been injured in an explosion in a crowded district of New York City.

The cause of the blast late on Saturday in Chelsea remains unclear. Mayor Bill de Blasio described it as "intentional" but said that there were no known links to terror, BBC reports.

The force of the blast blew out windows and could be heard several blocks away.

Another device, reportedly a pressure cooker rigged with wires, was later found in the same district.

New York's fire department said that of those injured, 24 were taken to hospital.

One received a puncture wound described as serious, while the rest suffered scrapes and bruises.

The explosion occurred around 21:00 (01:00 GMT on Sunday), outside a residence for blind people on West 23rd St.

Witnesses said people ran in all directions following the "incredibly loud" blast.

Some reports said the blast went off in a black metal construction toolbox, others that it was in a rubbish bin. Several blocks were shut by police but by 07:00 only 23rd St was closed, the New York Times reported.

A police official told the Times: "We don't understand the target or the significance of it. It's by a pile of dumpsters on a random sidewalk."

Mr de Blasio said: "The initial indication is this was an intentional act."

But he added: "We also want to be upfront saying that there is no evidence at this point of a terror connection to this incident."