The New York Police Department on Monday arrested 28-year-old Ahmad Khan Rahami in connection with the blast in the city's Chelsea neighbourhood that left 29 people injured on Saturday, reported The New York Times. The daily reported that he was taken into custody after being wounded in a shootout with police. Rahami, a naturalised United States citizen who was born in Afghanistan, was tracked after police spotted him on surveillance footage from the Chelsea area.

Earlier, NYPD spokesperson J Peter Donald had tweeted Rahami's photo without divulging further details about the nature of his involvement in the attacks. The 28-year-old is believed to be an American citizen of Afghan origin.

Meanwhile, United States President Barack Obama said, "We are extremely fortunate and grateful that nobody was killed. Our prayers go out to all of those who have been injured. We want to wish them a speedy recovery." Obama also commended the efforts of law enforcement officials and first responders for their "extraordinary professionalism and quick response, which surely prevented even more people from being hurt". He further said he had assured New York Mayor Bill de Blasio of federal support as the city's police continued its investigation into the incident.

On Sunday, the New Jersey police found a backpack with five explosive devices in a dustbin near a train station in Elizabeth, around 9.30 pm (local time), reported CNN. However, City Mayor Chris Bollwage said it was not related to Saturday's blast. One of the devices was disarmed by the bomb squad on Monday morning. Train services on both New Jersey Transit and Amtrak lines have been suspended.

Bollwage said the backpack was found outside a neighbourhood pub, around 500 feet from a train trestle. He said that no cell phone or electronic timing device was found in the bombs, adding, "Whoever threw it into the can was probably trying to get rid of it."

In another development, FBI spokesperson Mike Whitaker told The Guardian that the bomb that exploded on Saturday was made with a pressure cooker, cellphone and Christmas lights, and was packed with shrapnel. The same materials were used in another unexploded device that was found a few blocks away, near the train station in Elizabeth. According to BBC, similar bombs were used in 2013 at the Boston marathon that killed three people.