ELIZABETH, NJ (NBC NEWS) - - Law enforcement officials are searching for a 28-year-old suspected of playing a role in the bombings that have occurred over the last three days in New York and New Jersey.
Multiple senior law enforcement officials and an NYPD spokesperson early Monday identified Ahmad Rahami of Elizabeth, New Jersey, as a suspect. Sources told NBC News he was the man seen on video in Manhattan's Chelsea neighborhood, site of an explosion Saturday night.
The announcement came hours after a backpack that appeared to contain pipe bombs exploded as a police robot examined it near a New Jersey train station.
Mayor Chris Bollwage told reporters the bomb squad robot was "cutting into the device when it exploded" in the city of Elizabeth. A spokesman for Bollwage had earlier described the blast as a controlled detonation.
The explosion occurred shortly before 1 a.m. ET Monday. It was the second in New Jersey since Saturday morning and followed a bombing Saturday night in Manhattan that injured 29 people.
At around 6 a.m. ET, officials familiar with the investigation confirmed to NBC News that heavily armed FBI agents spotted at a fried chicken restaurant in Elizabeth were involved in the tri-state bombs probe.
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.
Authorities stopped a "vehicle of interest" in the New York blast at about 8:45 p.m. ET Sunday near the Verrazano-Narrows Bridge in New York, the FBI said. Five people were being questioned by the FBI early Monday, officials said.
None of the five people had been charged, and the investigation was ongoing, authorities told NBC News.
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Multiple senior law enforcement officials told NBC News that the suspicious device discovered Sunday night in Elizabeth looked similar in appearance to the one that exploded Saturday morning in Seaside Park, N.J.
The latest package was a backpack, and it was found by two men in a garbage can about 300 feet from the front door of a crowded pub in Elizabeth, according to Bollwage.
When they saw wires and pipes, they dropped it and immediately went to police headquarters, he said.
"We do not believe those two are involved," the mayor said. "We believe they did the right thing."
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."
New Jersey Transit suspended services between Newark Airport and the Elizabeth station, and Amtrak suspended service along parts of the Northeast Corridor.
The explosion Saturday night injured 29 people in Manhattan's Chelsea neighborhood. Less than three hours later, a "possible secondary device" was found a few blocks away on 27th Street while officers were combing the area.
The explosion sent a dumpster flying more than 150 feet down the sidewalk and shattered windows more than a block away, a senior law enforcement official said.
Investigators are analyzing possible similarities between the two devices found in Manhattan and the one that detonated in Seaside Park. All three devices apparently contained old-style mobile flip phones, according to officials familiar with the probe.
The New York explosion was determined to have been an "intentional act," authorities said.
New York Gov. Andrew Cuomo said it was clearly "an act of terrorism," although it hadn't been linked to an international terrorist group.
"A bomb going off is generically a terrorist activity," said Cuomo, who ordered 1,000 New York State Police and National Guard members deployed across the city.
Security had already been tightened in the city for the U.N. General Assembly, but the presence of officers throughout New York City after the blast will be "bigger than ever," Mayor Bill de Blasio said.