Heavily armed police and National Guard soldiers are deployed across New York City as the 8.4-million-strong city prepares to meet world leaders at the UN General Assembly on Monday.
The attack took place late Saturday in Chelsea, one of Manhattan’s trendiest neighborhoods, filled with bars, restaurants and luxury apartment buildings.
Police found a second bomb planted in four quarters that was safely defused and is currently being analyzed, officers said.
The blast came after a jihadist-linked news agency said Islamic State “soldiers” attacked with a knife in a U.S. mall, injuring eight people Saturday in Minnesota.
Local police said the attacker “in some way referred to Allah”, but the motives were unclear. The attacker was shot dead by an acting police officer. There was no speculation that this was due to the explosion in New York.
“The bomb blast in New York is obviously an act of terrorism, but it is not linked to international terrorism,” New York Governor Andrew Cuoma told reporters Sunday, visiting the crime scene.
“In other words, we find no connection with ISIS, etc.,” Cuoma said, referring to ISIS based in Iraq and Syria.
WATCH: The moment a powerful explosion struck a busy part of Chelsea in New York
The motive is unknown
New York City Police Chief James O’Neill said no person or group has yet claimed responsibility.
O’Neill said he could not say with “100 percent certainty” where the blast came from. American media report that he was taken to a landfill on 23rd Street, where major construction work is underway.
A hotline for parades has been set up. Police have video footage of the blast and have been searching for anyone seen in the area before the blast.
“We know this is a very serious incident, but we still have a long way to go to say what the motivation was behind it,” Mayor Bill de Blasio told reporters.
“It was a political motivation, a personal motivation. What was it? We don’t know yet,” he added, urging residents to be vigilant.
FBI spokesman William Sweeney said federal investigators would be browsing Internet traffic, individuals and organizations.
“We will consider everything,” he told a news conference. “We will look at social networks, all the incoming advice and leads. Everything that comes is considered. We do not reject anything.”
Security presence will be strengthened in New York, and nearly 1,000 more state and National Guard police will be deployed at airports, bus stations and subway stations, officials said.
The blast on 23rd Street, between Sixth and Seventh Avenues, caused “significant” damage, shattering glass and splinters across the street, but there is no structural damage to the buildings.
While the two devices installed in Manhattan look similar, they appear to be different from the pipe-bomb that exploded in nearby New Jersey on Saturday without causing casualties, officials said.
Of the 29 people injured in New York, 24 were taken to hospital with varying degrees of abrasions and abrasions from glass and metal. All were released, officials confirmed Sunday.
New York praises itself as the safest big city in America. Violent crimes are rare in Manhattan, and police say they have thwarted 20 terrorist plots since al Qaeda hijacking in 2001, destroying the Twin Towers.
New York Congressman Peter King said the fact that officials have not yet identified a known connection to the terrorists is not necessarily convincing.
“In many of these cases, we don’t know until two, three or four days later whether there is a connection to the terrorists,” he told CBS. “The fact that there is no evidence now means little,” he added.
Police cordoned off northern Chelsea around the crime scene, and dozens of officers were released on Sunday. An AFP photographer said there were many wreckage on 23rd Street, including rubble and glass.
“Today, special events are taking place across the city. Virtually all five districts. We have increased police presence at each of these events,” said New York City Senior Police Officer Carlos Gomez.
“We have also added more counter-terrorism officers as well as heavy weapons groups to some of these events. Teams from the Strategic Response Group as well as the Critical Response Command,” he said.
Turnbull urges New Yorkers to “not be afraid”
Prime Minister Malcolm Turnbull and his wife Lucy spoke to passengers in the famous city subway, urging them to “not be intimidated” as police continue to hunt down those responsible for planting a bomb in an elite Manhattan suburb of Chelsea.
“New Yorkers are living their normal lives, it’s normal,” Mr. Turnbull told reporters gathered near the Grand Army Plaza in Brooklyn.
“One thing we can’t do is allow people we seek to harm us, whatever their motivations, to intimidate us.
“We challenge them by going their own way.”
Australian Prime Minister Malcolm Turnbull talks to the media in New York (AAP) Source: AAP