Authorities were using a robot to disarm a device discovered at Elizabeth station south of Manhattan early on Monday morning when it exploded while further suspicious devices have been identified in the area, according to reports.
Local mayor Chris Bollwage said the FBI was on scene and investigating the incident.
He told CNN: “The robots that were going it to disarm it cut a wire and it exploded. I don’t know the technological aspect of that. I know there are other devices. I don’t know what they are made up of but they are going to have to be removed and all the fragments from the other pieces are going to have to be picked up so the FBI can investigate this fully.”
An improvised explosive device was detonated in a busy part of New York City late on Saturday evening injuring 29 people and a second device was found nearby and safely disarmed.
Governor of New York Andrew Cuomo said on Sunday the incident in the Chelsea area of Manhattan had not been found to be connected with international terrorism, although the investigation was at a very early stage.
Five people are being questioned in relation to the New York City blast.
Additional police and National Guard are patrolling the city, including at subway stations, airports and bus terminals.
Earlier on Saturday a pipe bomb exploded in New Jersey where a charity race was due to take place. No one was injured and the two are not thought to be connected although investigators are not ruling anything out.