At least 29 people were injured after an explosion rocked Manhattan’s Chelsea neighbourhood, at around 8:30pm on Saturday night.
New York’s fire department said those injured were treated for various cuts, scrapes and other minor injuries from shattered glass and other debris at local hospitals. One person was seriously injured but his condition was not disclosed.
New York’s mayor Bill de Blasio initially said the blast was "intentional" but that there was no evidence of a connection to terrorism.
"It is too early to determine what the incident was caused by. We believe it was intentional. A full investigation is under way," he said.
However, the governor of New York State, Andrew Cuomo, stated on Sunday that the explosion was "obviously an act of terrorism" although he added that so far it doesn't seem to have had an international component.
He told reporters, after touring the scene of the explosion, that "whoever placed these bombs, we will find and they will be brought to justice."
"They want to instil terror. They want to make you worry about going into New York. We're not going to let them instil fear."
Cuomo also stated that all the 29 people injured in the blast have been released from hospital.
Police combing the scene around the explosion found a pressure cooker connected to a cell phone with wires attached, Reuters reported, citing US network CNN. The device was removed safely.
Pic of the 2nd bomb (pressure cooker with wires. pic.twitter.com/LBdbce7GUs
— Mike Cernovich (@Cernovich) September 18, 2016
The White House said President Barack Obama, who was attending a congressional dinner had been informed.
"The president will be updated as additional information becomes available," an official from the White House said.
Both presidential nominees Republican candidate Donald Trump and his Democratic rival Hillary Clinton reacted to the blast.
"I must tell you that just before I got off the plane, a bomb went off in New York. And nobody knows exactly what's going on," Trump told supporters at a rally in Denver. Trump called for "tough" measures to be taken, without specifying.
"We better get very tough folks. We better get very, very tough," he said.
Clinton said she was waiting for more details to emerge.
"I think it's always wiser to wait until you have information before making conclusions," she said
New York’s mayor also said there was no evidence linking the Manhattan explosion to a pipe bomb blast in nearby New Jersey, hours earlier.
An explosive device went off in a trash can in a New Jersey beach town on Saturday, along the route of a charity race to benefit military veterans. About 5,000 people were set to run the race.
The pipe bomb exploded in a trash can, along the route of a charity race to benefit military veterans, but no injuries were reported. Investigators are treating the New Jersey blast as a possible act of terrorism.