Police seek clues in New York blast that hurt 29; no terrorism links found

New York: New York Governor Andrew Cuomo said on Sunday there was still no indication that an explosion that injured 29 people in Manhattan on Saturday was linked to international terrorism, while investigators scoured the scene of the blast.

FBI investigators were to examine remnants of the bomb plus an unexploded device found four blocks away and another device that exploded about 80 miles (130 km) away in New Jersey on Saturday to see if they were connected, Cuomo said.

No international group had claimed responsibility "but it is very, very early in the investigation," the state governor told reporters, reiterating what New York City Mayor Bill de Blasio had said hours after the blast.

"A bomb exploding in New York is obviously an act of terrorism, but it`s not linked to international terrorism. In other words, we find no ISIS connection, et cetera," Cuomo said, referring to the Islamic State.

With world leaders due to arrive in the city ahead of the U.N. General assembly, some 1,000 additional state police and National Guard officers were being sent to the city to patrol transportation hubs as a precaution, Cuomo said.

Heads of state and government begin six days of speeches in New York on Tuesday, with some dignitaries arriving early for preliminary events.

A sweep of the neighborhood following the blast had turned up another device four blocks away consisting of a pressure cooker with wires attached to it and connected to a cell phone.

Pressure cooker bombs were used in the 2013 Boston Marathon bombing that killed three people and wounded more than 260.

The New Jersey explosion came from a pipe bomb, officials said. A U.S. official familiar with information circulating inside the government said the motive remained unknown and insufficient evidence had been gathered to link the two New York bombs. There was no evidence to connect them to the New Jersey blast, said the source, who spoke on condition of anonymity.

"From what we know now, and it`s limited, almost anybody could have fabricated these bombs and used cellphones as timed detonators," said another U.S. official familiar with the inquiry. "There are instructions all over the internet, and the crudity, positioning, and relative ineffectiveness of these does not suggest that a more sophisticated group played any role in this."

The U.S. Federal Bureau of Investigation (FBI) was taking evidence from all three devices to its special crime laboratory in Quantico, Virginia, said Cuomo, adding that he had been briefed by "all the relevant agencies."

"We will find who planted these explosives and they will be punished. ... We will not allow these type of people and these type of threats to disrupt our life in New York," Cuomo said.

Most of the injured were treated for minor injuries including shrapnel wounds and released, though police listed one injury as serious.

"When you see the damage, I think we were fortunate that there were no fatalities," Cuomo said.

New York police, the FBI and the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives converged on the site for their first daylight view of the explosion, closing several blocks of West 23rd Street to traffic.

Investigators cordoned off the area with yellow crime scene tape and placed dozens of numbered evidence markers on the ground. Neighborhood residents who could show identification were allowed back into their homes.

The blast, described by one neighbor as "deafening," reverberated through the Chelsea district of Manhattan around 8:30 p.m. (0030 GMT Sunday) on 23rd Street, a block of mostly commercial spaces at street level with residential floors above. The Flatiron Building, a New York landmark, is about 500 yards (meters) away.

It happened outside the Associated Blind Housing facility at 135 W. 23rd Street which provides housing, training and other services for the blind. The same block is home to a Roman Catholic Church with a neoclassical facade, a Basque restaurant, a showroom for exercise cycles and a small hotel, among other businesses.

The explosion quickly became an issue in the presidential race. Republican candidate Donald Trump told an audience, "We better get very tough, folks." Democratic rival Hillary Clinton said in a statement she had been briefed but would wait until she had more information before commenting further.