"There was a suspicious package with multiple improvised explosive devices at the Elizabeth Train Station in NJ," FBI's Newark office tweeted after the suspicious backpack was found last night near the Elizabeth train station.
"In the course of rendering one of the devices safe, it detonated. There are no injuries and law enforcement personnel are at the scene processing evidence," it added.
The backpack was noticed in a trash can by two men, who reported it to the police after they saw "wires and a pipe" in it, Chris Bollwage, mayor of Elizabeth, New Jersey, said.
"This was an explosive device containing as many as five explosives. Based on the loudness, I think people could have been severely hurt or injured if they had been in the vicinity."
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Bollwage said he was "extremely concerned for the residents of the community" if "someone could just go and drop a backpack into a garbage can that has multiple explosives in it."
As many as 29 people were injured after a blast in Chelsea district of Manhattan, New York, yesterday, while a second bomb that was discovered nearly four blocks away was defused successfully by the bomb disposal squad.
The New York explosion was determined to have been an "intentional act," authorities said, adding, five people were being questioned by the FBI but none has been charged and the investigation was ongoing.
New York Governor Andrew Cuomo said it was clearly "an act of terrorism," although it hadn't been linked to an international terrorist group.
Security had already been tightened in the city for the ongoing UN General Assembly, but the presence of officers throughout New York City after the blast will be "bigger than ever," New York Mayor Bill de Blasio said.
Several law enforcement officials told NBC News that they are concerned that an active terrorism cell with multiple players could be at work in the New York-New Jersey area.
Officials said that the suspicious device discovered Sunday night in New Jersey appeared appeared similar to a device that exploded earlier Saturday morning in Seaside Park.