Multiple Explosions Rock the United States Leaving 29 Injured | WATCH

A bomb attack on a crowded sidewalk in the bustling Chelsea neighborhood of Manhattan on Saturday night was a terrorist act, officials say, but no links have been found to global groups and the motivation remains unclear.

The blast, which occurred on Saturday night in Manhattan injured 29 people who have all been released from hospital.

“Was it a political motivation? A personal motivation? We do not know,” said Mayor Bill de Blasio.

Blasio however, described the explosion as “an intentional act”. “Whatever the cause, New Yorkers will not be intimidated,” he added.

According to New York Times, the impact shattered windows, damaged cars and sent crowds running from the scene at an hour when Chelsea, always a popular destination, was filled with residents and tourists.

Watch CCTV video of the moment of the explosion:

The blast in Manhattan follows the discovery of a pipe bomb in New Jersey earlier in the day.

Law enforcement sources said the pipe bomb was hidden in a bin near the course of a scheduled 5km race in support of the US Marines and sailors in Seaside Park, down the east coast from New York.

Although no one was injured, there were other devices that failed to explode.

According to a spokesman for the Ocean County prosecutor’s office, Al Della Fave, it was “obvious” that the blast was meant to affect the run.

“I think we can assume that, considering the location of the device right along the run route where, if it was just a matter of minutes in terms of difference, there would have been a good number of people running past that explosive device,” Fave said when asked if Marines and their families had been targeted.

A few hours after the New York attack, authorities found and removed what they described as a second explosive device four blocks away, raising the possibility that two bombs had been planted in the heart of the city.

New York Governor Andrew Cuomo said: “Whoever placed these bombs, we will find them and they will be brought to justice.”

“A bomb exploding in New York is obviously an act of terrorism,” he added.

Watch the aftermath of the explosion:

Credits: The Guardian | BBC | NY Times