New York explosion: Second device found in Manhattan after blast injures at least 29

An explosion in a crowded Manhattan neighborhood has left 29 people injured, with authorities saying a second nearby site is also being investigated.

Mayor Bill de Blasio has called the blast an "intentional act," but said there was no terrorist connection.

"Tonight, New York City experienced a very bad incident," de Blasio said at a news conference near the scene in Chelsea. "We have no credible and specific threat at this moment. "

De Blasio described the blast was "an intentional act" but insisted there was no terrorist connection and the explosion wasn't related to a pipe bomb explosion earlier in the day in New Jersey at a charity run.

A second device is being investigated by officers were four blocks from the scene, which appears to be a pressure cooker attached to wiring and a cellphone. The device was reported to have been found inside a plastic bag on West 27th Street.

New York officials have said the incident was not due to a gas leak

Early reports said there had been 29 injuries in the New York City incident, none reported to be life-threatening.

Witnesses said the blast was strong enough to blow out the windows on the lower floors of the building. It came on a warm Saturday night in a part of Manahattan that can normally be expected to be busy with foot-traffic as residents and tourists move about on foot.

At least three people were seen being taken away from the apparent scene of the blast in ambulances. A car seen driving through the area had its rear window blown out.

Police officers and medical services converged on the area near the intersection of 7th Avenue and 23rd Street and were seen pushing bystanders away from the area and diverting traffic. In a bulletin the authorites warned anyone traveling in the vicinity to “expect extensive traffic delays and emergency personnel in the area” due to police activity. There were also widespread disruptoins to subway travel in Manhattan.

Police spokesman J. Peter Donald said on Twitter that the explosion happened at about 8:30 p.m. Chris Gonzalez, visiting from Dallas, was having dinner with friends at a restaurant in the area.

“We felt it, we heard it, the restaurant went real quiet, the 26-year-old Mr Gonzalez told the Associated Press. ”It wasn't like jolting or anything, everyone just went quiet.“

Witnesses say FBI and Homeland Security officials, along with the ATF arson and explosive task force are also at the scene. Officials indicated that there was no suggestion of a gas leak. Officials said that President Barack Obama was following developments from the White House.

While it was too soon for the authorities to say definitively that one more devices had deliberately planted, officials said an anti-terrorism unit had been dispatched to the scene. Investigators will also be aware of the New Jersey incident that happened earlier on Sunday morning.

That involved a a pipe bomb exploded in Seaside Park, New Jersey, along the route of a US Marines, 5-K charity run which was quickly cancelled.

The local Ocean Country prosecutor’s office confirmed the explosion and said there were no injuries or damage to nearby structures.

A nearby boardwalk and beach were immediately cleared by the authorities and sniffer dogs were brought in to search the area of other devices.

The device at the centre of the scare was relatively small and had been placed inside a plastic bin liner that was on the route of the third annual Semper Five charity run, the start of which had been delayed because of late sign-ins by some of the runners.

Officials said a second device had been found near to the one that exploded, according to the local news site, NJ.com, quoting Al Della Fave, a spokesman for the prosecutor. There was no immediate confirmation on whether it had been detonated. But a bomb team was already on site to “make safe” that device, officials noted.

The apparent terror attempt immediately evoked the Boston Marathon bombing three years ago when Tamerlan and Dzhokhar Tsarnaev planted bombs in pressure cookers near the finish of the world famous race, killing three people and injuring more than 260.

Runner Adam Carswell of Toms River, New Jersey, told NBC 4 New York he saw the smoke rising from the garbage can after the explosion. “It was a big puff of smoke, fairly large,” he said, expressing anger that someone may have planted the device to harm people.

Officials were giving thanks for the back-up at the registration desks for the run, noting that had it begun as scheduled some of the runners would have been passing where the bag had been placed at the moment that it exploded.

The incident took place on a day of brilliant sunshine along the Jersey Shore, with plenty of onlookers on hand to enjoy the race in Seaside Park. Residents around the near vicinity were evacuated and only allowed back to their homes once the authorities were certain no other devices were remaining.