New York: A powerful explosion on Sunday rocked New York's upscale neighbourhood injuring 29 people, in what the mayor described was an "intentional act", hours before world leaders arrive here for the UN General Assembly session even as police also found a pressure cooker with wires nearby.
The explosion - which came hours after a pipe bomb went off in a garbage can in New Jersey - occurred in Manhattan's Chelsea neighbourhood at 23rd St. And 6th Avenue, a busy residential and commercial area frequented by tourists and city residents, around 8:30 pm (local time) yesterday.
President Barack Obama, who is set to visit the city for the UNGA session beginning tomorrow, has been apprised of the explosion, a White House official said.
New York City Mayor Bill de Blasio said the number of people injured is now 29 but none is life threatening except one who is in "serious" condition.
The Mayor described the explosion as an "intentional act" but said there is no evidence at this point of a terror link.
He said the city "experienced a very serious incident" and injuries are significant but added that there is "no evidence at this point of a terror connection" even as early indications suggest "this was an intentional act".
"There is no specific and credible threat at this time from any terror organisation", he said.
The explosion took place at usually a busy time of the weekend in one of the most fashionable districts of Manhattan packed with bars, restaurants and luxury apartment blocks, and comes a week after America's financial capital with an 8.4 million population marked the 15th anniversary of the 9/11.
Authorities said "extensive search" is being conducted in the area and the neighbourhood and ruled out gas as the reason for the explosion.
Security is already tight in the city, with nearly 190 world leaders set to arrive in the city for the nearly week- long annual UN General Assembly session.
A second Manhattan site is under investigation, Blasio said while addressing a press conference at the scene.
Local officials said the device at a second location few blocks away in Chelsea appears to be a pressure cooker, with dark coloured wiring coming out of the top centre of the device. The device is connected by silver duct tape to a small device attached to the outside of the pressure cooker.
The suspicious device on West 27 Street in Chelsea was later safely removed by the NYPD Bomb Squad.
The Mayor also added that at this point there is "no specific connection" to the incident in New Jersey earlier in the day in which an explosion occurred in a garbage can during a Maine Corps charity run but there were no injuries as the race got delayed and was later cancelled.
Blasio said: "We are not going to let anyone change us, intimidate us."
The New York Times quoted an official as saying that "the second device, on West 27th Street, was described as resembling a pressure cooker like the one used in the Boston Marathon bombings in 2013".
The official said investigators "don't have any suspects", and are not questioning anyone.
New York City new Police Commissioner James O Neill, who had his first day at the city's police chief yesterday, that the "exact cause of the explosion has not yet been determined" and personnel from the police department, FBI, bomb squad and counter-terrorism departments are on the scene.
The Police Commissioner added that a "second site" is being treated at 27th street between 6th and 7th avenues by the police but did not provide more details.
Police said investigations are ongoing and had advised people to avoid the area.
As a "precautionary measure" residents were asked to "stay away" from windows "until we clear the area of a suspicious package", they said, adding they were not evacuating the area.
"The president (Obama) has been apprised of the explosion in New York City, the cause of which remains under investigation. The president will be updated as additional information becomes available," a White House official said.
Obama is scheduled to travel to New York and stay in the city for the next several days to attend the United Nations General Assembly session.
Of those injured, 24 have been taken to hospitals with scrapes and abrasions from glass and metal, Fire Department commissioner Daniel Nigro said.
Police said they have video from the scene and are collecting more, according to CNN. However, police said it is too early to give out details beyond saying the explosion was outside, in a dumpster or receptacle of some kind. They are processing the scene.
Police are combing through the video and that it likely shows someone dropping or leaving something behind, leading them to the conclusion this was an intentional act.
An eyewitness was quoted as saying that he was having dinner when an explosion rocked the area.
"(I) felt a loud explosion and I felt like a lightning bolt struck the building. It, like, shook the ground," he said. "Everybody ran out of the restaurant into the street. The whole city was in the street."
Democratic presidential nominee Hillary Clinton was also briefed about the New York explosion. She was in the Washington DC addressing a Congressional event.
The 68-year-old former secretary of state cautioned against drawing conclusions on the New York explosion before facts are in.
Asked what she thought of her Republican opponent Donald Trump immediately referring to the explosion as a bomb earlier, Clinton said: "I think it's important to know the facts about any incident like this."
Referring to the explosion, Republican presidential nominee Donald Trump had said "a bomb went off" in New York "just before I got off the plane."
"We better get very tough. We'll find out. It's a terrible thing that's going on in our world and in our country and we are going to get tough and smart and vigilant. We'll see what it is," Trump told supporters at an election rally in North Carolina.