Footage has emerged showing the dramatic moment of the blast in Manhattan that left 29 people injured. The video was caught on the security surveillance cameras of nearby businesses.

The blast, which is thought to have been centred in a dustbin, happened at 8.30pm Saturday (1.30am BST) local time on 23rd Street, between 6th and 7th Avenues.

Just seconds before, people can be seen walking along the street. The blast then shatters glass, prompting people to flee in panic. The video footage captures scenes of chaos and the sound of police sirens in the background.

At least 29 people were injured in the explosion, which NYC mayor Bill de Blasio has described as an "intentional act", though he dismissed any links to Islamic State (Isis).

De Blasio said: "We know there was a bombing. That much we do know. We know it's a very serious incident. But we have a lot more work to do to be able to say what kind of motivation was behind this.

"All possible theories of what's happened here and how it connects will be looked at but we have no specific evidence at this point in time. We will keep the public informed every step of the way," he told reporters.

All the victims of the attack have been released from hospital and are expected to make a full recovery. Police discovered and defused a second device nearby in the Chelsea district of Manhattan, Sky News reported.

The New York Governor confirmed 1,000 extra police and National Guard officers would be deployed to airports, bus stations, subways and all major transit zones in the area, however he urged New Yorkers to continue as normal.

The Mayor called on the public to be vigilant and pass on any information that may be relevant to the ongoing investigation to police.

"Be vigilant because the police need your help and if you see anything that might be pertinent to this case, we need you to call it in," he said.

New York blast
A view of a mangled dumpster at the site of an explosion that occurred on Saturday night in the Chelsea neighbourhood of New York Reuters