Dozens of people were injured yesterday in the Chelsea neighbourhood of Manhattan in an explosion that New York Mayor Bill de Blasio called "an intentional act".
At least 29 people suffered non-life-threatening injuries in the blast, which occurred on the street and not inside a building, according to the New York Police Department. One person was seriously injured, said Daniel Nigro, the New York fire commissioner.
US media reported that a pressure cooker with tape, wires and a cell phone had been found at a second location a few blocks away.
Police officers, firefighters and other first responders rushed to the blast scene, which closed a major roadway, forced people out of nearby buildings and brought onlookers to the area.
De Blasio said that in the initial hours after the explosion, authorities had found "no evidence at this point of a terror connection to this incident".

"The exact nature and cause of this explosion has not yet been determined," James O'Neill, the New York police commissioner marking his first day in the position, said at the news conference. O'Neill did say that natural gas had been ruled out as a possible cause.De Blasio said that the explosion was "an intentional act," but during a briefing, he said little other information was available because the investigation was in its early stages.
The New York Police Department's counterterrorism bureau said it was responding to the explosion, which came hours after a pipe bomb exploded in a Jersey Shore garbage can shortly before a scheduled charity race there benefiting Marines and Navy sailors.
De Blasio said authorities had not found anything connecting the Chelsea and New Jersey incidents. He also said that there was no specific, credible threat against New York from any terror group.
While O'Neill said authorities were still trying to determine what, precisely, exploded, the New York Police Department's counterterrorism bureau posted a photo online showing what appeared to be a dumpster or garbage container mangled by a blast.

Police arrive on the scene of an explosion in Manhattan's Chelsea neighborhood. Photo / AP

MSNBC reported that law enforcement officials said there was surveillance video showing a person dropping something into the dumpster before the explosion.
The FBI said it was involved in the response and the Bureau of Alcohol, Tobacco, Firearms and Explosives said its arson and explosives task force was being dispatched to the explosion scene.
Police in New York also reported that they had found "a possible secondary device" a few blocks away from the explosion scene.
Officers were directing people away from this other intersection, and one could be heard telling pedestrians that "there is a possible explosive" in the area.
Three law enforcement sources told NBC News that investigators at the second location were examining what appeared to be a pressure cooker with "tape, wires and a cell phone" left out on the pavement.
The explosion in the area of 23rd Street between Sixth and Seventh avenues happened at about 8.30 pm local time, police said. "Several" of those injured were brought to area hospitals, Peter Donald, a police spokesman, posted on Twitter.
Photos and accounts posted on social media showed large crowds - as well as a large law enforcement presence - in the area near where the explosion occurred.
Soleil Filomena, 64, was leaving a convenience store at 7th Ave and 23rd street when she heard the explosion.
"It was so loud it just went through my whole body," she said. "People started running up 23rd Street and I started running with them."

A police officer escorts an injured man away. Photo / AP

Filomena said she saw a "big black cloud in the sky". After the explosion, she said her "ear was ringing for 15 minutes".
When Keith Salomon of Delaware felt the explosion, he was having dinner a block and a half from blast. His chair and table shook and he saw people being taken away in ambulances.
"We didn't know what it was and so at first we just kept eating. But then we realised something was wrong."
Others did not hear the explosion but saw the aftermath. When Jacob Schulman left his apartment a few blocks away shortly before 9 pm, he saw people running and screaming.
"I didn't know what was going on but everyone looked so panicked I started running too," said Schulman, 26, who has lived in the neighbourhood since 2014.
Two blocks from the blast scene, a group of people emerged from a screening of the animated movie Beauty and the Beast and saw the flashing lights.
One man who came out of the theatre said he could not hear anything and had no idea about the explosion not far from where he was sitting.
President Barack Obama was attending an annual dinner of the Congressional Black Caucus Foundation and was briefed on the situation in New York. He will be updated as more information becomes available, a White House official said.
The explosion in New York comes as foreign leaders, including many heads of state, are heading to Manhattan for the United Nations General Assembly. Secretary of State John Kerry arrived, while Obama is scheduled to head to the city tomorrow.
This annual meeting - held more than 3.2km from the site of the explosion in Chelsea - is traditionally a tricky time for New York, as many roads are shut down and the heavy security leads to increased traffic.
Speaking in Colorado not long after the explosion, Republican presidential candidate Donald Trump quickly commented on the situation before much information was known. "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," said Trump shortly after getting off of his plane. His comments were made before authorities confirmed the nature of the explosion. Trump told the crowd, "we better get very tough, folks."
Meanwhile, in his address, Obama said he would consider it "a personal insult" if the African-American community does not turn out to vote in great numbers in November and help carry on his legacy by supporting Democratic nominee Hillary Clinton. "If you care about our legacy, realise everything we stand for is at stake. My name may not be on the ballot, but our progress is on the ballot."

Heavily armed police officers stand guard in the Armed Forces recruitment centre island in New York's Time Square. Photo / AP

Democratic presidential nominee Hillary Clinton issued a statement saying she strongly condemns what she characterised as "apparent terrorist attacks" in Minnesota, New Jersey and New York.
"Law enforcement officials are working to identify who was behind the attacks in New York and New Jersey, and we should give them the support they need to finish the job and bring those responsible to justice," Clinton said, adding: "We will not rest until that happens."
The former Secretary of State noted that Isis (Islamic State) had asserted responsibility for the stabbings of nine people inside a shopping centre in St Cloud, Minnesota, about 110km northwest of Minneapolis.
"This should steel our resolve to protect our country and defeat Isis and other terrorist groups," Clinton said.

Clinton's statement followed remarks to reporters on her campaign plane on Sunday in which she cautioned against rushing to conclusions about the attacks and criticised her Republican opponent, Donald Trump, for quickly telling an audience that an explosion in New York was a bomb that served as a reminder for the United States to "get very tough"."I have laid out a comprehensive plan to do that."
Today, New York Governor Andrew Cuomo, said there was "no evidence of an international terrorism connection" to the incident in the Chelsea neighbourhood of Manhattan, where an "intentional" blast apparently was caused by an improvised explosive device on Sunday. But Cuomo said "a bomb exploding in New York is obviously an act of terrorism".
In her statement, Clinton said her plan to combat terrorism "includes launching an intelligence surge to help identify and thwart attacks before they can be carried out, and to spot lone-wolf attackers."
"We also need to work with Silicon Valley to counter propaganda and recruitment efforts online," she said. "Americans have faced threats before, and our resilience in the face of them only makes us stronger. I am confident we will once again choose resolve over fear."


Yesterday, Republican nominee Donald Trump appeared to pre-empt New York City officials when he declared that a "bomb went off" in New York City before officials had released details.
Trump made the comments around 9.10 pm, shortly after the explosion in Manhattan's crowded Chelsea neighbourhood and as emergency officials were responding 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 said.
"It's a terrible thing that's going on in our world, in our country," he added, "and we are going to get tough and smart and vigilant. . . . We'll see what it is. We'll see what it is."

Trump surrogate New Jersey Governor Chris Christie defended Trump's comments.
"Well, listen, I don't think you have to defer when saying that there was an explosion and a bomb in New York," Christie said. "I mean, everybody knew that, and it was being reported on television. . . . So there's a difference. Now, you shouldn't attribute it to any particular organisation or group if you don't have the facts or information to do that. But I think that what Donald did was perfectly appropriate."
Christie said that he does not know who is responsible for the bombings in New York and New Jersey, but he does know what to call the attacks.
"You can call them whatever you want - they are terrorism, though," Christie said on CNN. "There's no doubt about that. They're terrorism. Now, who's responsible and what the motive was is something else that, hopefully, we're going to find out in the days ahead."
Republican running-mate Governor Mike Pence says "we're all troubled in our hearts" about explosions in New Jersey and New York and a knife attack in Minnesota. Pence says that whether the incidents were acts of terrorism or inspired by terrorists, "prayer and vigilance is the order of the day".