New York officials have identified a suspect wanted for questioning over Saturday's blast in the Chelsea area of the city.
The man has been named as New Jersey resident Ahmad Khan Rahami, 28, a naturalised US citizen from Afghanistan.
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Device explodes outside US train station
New Jersey's mayor says a suspicious device exploded outside a train station early Monday. The device was one of five that two men found in a trash can.
Mayor Bill de Blasio warned he could be armed and dangerous.
"We need to get this guy in right away," Mr de Blasio said on CNN.
![One of the devices exploded during an attempt to disarm it.](/web/20160921002117im_/http://www.smh.com.au/content/dam/images/g/r/j/u/d/b/image.related.articleLeadwide.620x349.grjs9u.png/1474296167785.jpg)
"My experience is once the FBI zeroes in on someone, they will get them."
The development came hours after five more suspected explosive devices were found in a backpack near a train station in New Jersey, with one device accidentally detonated by authorities during an attempt to disarm it.
Rahami is wanted for questioning over a powerful explosion which rocked Manhattan's popular Chelsea neighbourhood late on Saturday when a pressure-cooker bomb packed with shrapnel detonated. A similar unexploded device was found a few blocks away later that night.
The Chelsea blast followed a pipe bomb explosion on Saturday morning along the route of a running race in the New Jersey beach town of Seaside Park. No one was injured in that blast.
![Bomb squad personnel at the scene of an explosion in Elizabeth, New Jersey.](/web/20160921002117im_/http://www.smh.com.au/content/dam/images/g/r/j/u/c/t/image.related.articleLeadwide.620x349.grjs9u.png/1474296167785.jpg)
The five new devices were found in the city of Elizabeth, about 40 minutes away from New York City.
Two men had just left a restaurant on North Broad Street at around 8.30pm local time, the New York Times reported, when they saw a backpack sitting in a rubbish bin and opened it up.
![The scene where the suspicious devices were found.](/web/20160921002117im_/http://www.smh.com.au/content/dam/images/g/r/j/u/c/u/image.related.articleLeadwide.620x349.grjs9u.png/1474296167785.jpg)
Christian Bollwage, the Mayor of Elizabeth, said the men saw wires and a pipe in the bag and dropped it on the street before they sought help.
Police and agents from the Federal Bureau of Investigation (FBI) responded, bringing two bomb robots to inspect the devices. One robot cut a wire on one of the devices, which caused it to explode.
![Ahmad Khan Rahami.](/web/20160921002117im_/http://www.smh.com.au/content/dam/images/g/r/j/w/9/s/image.related.articleLeadNarrow.300x0.grjs9u.png/1474329469473.jpg)
"The robots that were going in to disarm it cut a wire and it exploded," Mr Bollwage told CNN.
"I don't know the technological aspect of that. I know there are other devices, I don't know what they're made up of, but they're going to have to be removed. All of the fragments of the other piece are going to have to be picked up so the FBI can investigate this fully."
![An emergency alert sent to mobile phones in the New York area on Monday.](/web/20160921002117im_/http://www.smh.com.au/content/dam/images/g/r/j/w/c/a/image.related.articleLeadNarrow.300x0.grjs9u.png/1474296167785.jpg)
There were no immediate reports of injuries or damage to the surrounding area. One robot was destroyed and another was damaged in the explosion.
One witness told the Times there was screaming and confusion after the device exploded.
"People were screaming, a woman yelled, 'what the hell was that'," Dean Fage said. "I felt it in my chest. I thought when they find bombs they take them and detonate them somewhere else."
The other four devices will be seized and inspected by the FBI. It is thought the immediate area surrounding where the devices were found will remain closed for 24 hours
Trains in the area were suspended early on Monday between the international Newark Liberty Airport and Elizabeth. Amtrak trains heading to New Jersey were being held at New York Penn Station, officials said, while New York-bound Amtrak trains were being held in Trenton, around an hour to the south-west of Elizabeth.
Train passengers reported being stuck on Amtrak and NJ Transit trains for hours on Sunday night, while some trains moved in reverse to let passengers off at other stations.
Amtrak said 2400 passengers were affected and trains were being brought into other stations for people to get other transportation.
The discovery of the suspicious package comes a day after an explosion in Manhattan injured 29 people, and an unexploded pressure-cooker device was found four blocks away. Also on Saturday, a pipe bomb exploded about an hour from the Elizabeth train station in Seaside Park, New Jersey, forcing the cancellation of a military charity run. Officials said it didn't appear that those two incidents were connected, though they weren't ruling anything out.
Mr Bollwage said he wasn't willing to say that Elizabeth had become a target, and that it was possible someone was trying to get rid of the package by throwing it away.
"I'm extremely concerned for the residents of the community, but more importantly extremely concerned for everyone in the state and country where someone can just go and drop a backpack into a garbage can that has multiple explosives in it with no timers and then you have to wonder how many people could have been hurt,'' Mr Bollwage said.
He said the devices didn't appear to have a timer or a mobile phone on them to activate them remotely.
with AAP