Mayor Bill de Blasio called the blast an ‘intentional act’ but said there was no terrorist connection.
“Tonight, New York City experienced a very bad incident,” he said at a news conference near the scene in Chelsea. “We have no credible and specific threat at this moment.”
He said the blast was ‘an intentional act’ but tried to calm any fears among nervous New Yorkers, saying there was no evidence of a link to terrorism, and no connection with a pipe bomb explosion earlier on Saturday at a New Jersey charity run.
A law enforcement official said the second device that officers were investigating four blocks from the scene appeared to be a pressure cooker attached to wiring and a mobile phone.
The source said the device was found inside a plastic bag on West 27th Street.
The official said the explosion appears to have come from a construction toolbox in front of a building. New York officials said the incident was not due to a gas leak, as some initial reports had suggested.
Photos from the scene show a twisted and crumpled black metal box.
The blast happened on West 23rd street, in front of a residence for the blind, near a major thoroughfare with many restaurants and a Trader Joe’s supermarket.
Witnesses say the explosion at about 8:30pm local time blew out the windows of businesses and scattered debris in the area. Officials said no evacuations were necessary.
Fire Department Commissioner Daniel Nigro said several people were taken to hospital with injuries.
One of those hurt suffered a puncture wound that was considered serious. He said the other injuries were minor, described as scrapes and bruises.
A number of New York City subway routes were affected by the explosion.
Rudy Alcide, a bouncer at Vanity Nightclub at 21st Street and 6th Avenue, said he, at first, thought something large had fallen.
“It was an extremely loud noise, everything was shaking, the windows were shaking, it was crazy,” he said. “It was extremely loud, almost like thunder, but louder.”
The White House said President Barack Obama has been told of the explosion and will be updated as additional information becomes available.
In St Cloud, Minnesota, police said multiple people were injured at a shopping mall on Saturday evening in an attack that possibly involved both a shooting and stabbing. The suspect was believed to be dead.
Hillary Clinton said she has been briefed ‘about the bombings in New York and New Jersey and the attack in Minnesota.’
The Democratic presidential candidate said the nation needs to support its first responders and ‘pray for the victims.’
She said: “We have to let this investigation unfold.”
The reports of a possible blast come hours after a pipe bomb exploded in Seaside Park, New Jersey, shortly before thousands of runners participated in a charity race to benefit Marines and sailors. No injuries were reported.