NEW YORK — Gov. Andrew Cuomo said Sunday a blast that injured 29 people in Manhattan was caused by some kind of bomb, but the attack didn’t appear to be linked to international terrorism.

Cuomo, speaking near the scene of the Saturday night blast, told reporters a second device found blocks away from the first explosion appeared “similar in design” to the first, though investigators are still testing its remnants after it was removed by a bomb squad robot and blown up at a police facility in the Bronx.

The bombing rocked the city’s Chelsea neighborhood, a mostly residential part of Manhattan’s west side known for its art galleries and large gay population. Witnesses described hearing a deafening blast, and surveillance video footage captured images of nearby windows being blown out by the explosion as people sprinted away from the scene.

“We will find whoever planted these explosives and they will be punished,” said Cuomo, a Democrat. He said all 29 people who were injured have been treated and released from a hospital.

New York Governor Andrew Cuomo and New York City Mayor Bill de Blasio arrive at the scene of an explosion on West 23rd Street2016 in New York. An explosion rocked one of the most fashionable neighborhoods of New York on September 17 night, injuring 29 people, one seriously, a week after America's financial capital marked the 15th anniversary of the 9/11 attacks. Mayor Bill de Blasio indicated the blast was not accidental, even if there was no known link to terrorism. The blast occurred in Chelsea -- an area packed with bars, restaurants and luxury apartment blocks -- at a typically bustling time of the weekend.AFP PHOTO / Bryan R. SmithBRYAN R. SMITH/AFP/Getty Images ORG XMIT: 'Intentio

New York Governor Andrew Cuomo, left, and New York City Mayor Bill de Blasio arrive Sunday at the scene of an explosion on West 23rd Street in the Chelsea neighborhood in New York.| AFP PHOTO

Members of the FBI’s Joint Terrorism Task Force are investigating the blast along with New York Police Department detectives, fire marshals and other federal investigators. As a precaution, Cuomo said he was deploying an additional 1,000 state troopers and members of the National Guard throughout New York City.

The first device, which exploded about 8:30 p.m. on West 23rd Street, appeared to have been caused by an improvised explosive device placed inside a toolbox in front of a building undergoing construction, according to a law enforcement official who spoke to The Associated Press on condition of anonymity because the official wasn’t authorized to discuss an ongoing investigation.

The second device, found later inside a plastic bag on West 27th Street, appeared to be a pressure cooker with wiring and a cellphone attached to it, the official said. A spokesman for the Bureau of Alcohol, Tobacco, Firearms and Explosives in New York said investigators are examining the remnants of the device to determine how it was comprised, including whether it was real or fake.

Investigators were also probing whether the Manhattan blast was in any way related to a pipe bomb explosion in Seaside Park, New Jersey, before a charity 5K race to benefit Marines and sailors earlier Saturday. The race was canceled and no one was injured.

Mayor Bill de Blasio, speaking at the scene of the explosion Saturday night, said that there didn’t appear to be a connection between the two incidents. He called the explosion an “intentional act” but said there was no known “specific and credible threat against New York City.”

“Now, I want to be clear: Whatever the cause, whatever the intention here, New Yorkers will not be intimidated,” he said.

Chris Gonzalez, visiting from Dallas, was having dinner with friends at a restaurant in the area.

“We felt it. We heard it,” Gonzalez said. “It wasn’t like jolting or anything. Everyone just went quiet.”

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,” he said. “It was extremely loud, almost like thunder but louder.”

A police officer escorts an injured man from the scene of a possible explosion on West 23rd Street in New York. | AP photo

A police officer escorts an injured man from the scene of a possible explosion on West 23rd Street in New York. | AP photo

Police and first-responders work near the site of a bomb explosion Saturday on West 23rd Street in New York. | Bryan R. Smith / AFP/Getty Images

Police and first-responders work near the site of a bomb explosion Saturday on West 23rd Street in New York. | Bryan R. Smith / AFP/Getty Images

Police arrive on the scene of an explosion Saturday in Manhattan's Chelsea neighborhood in New York. | Andres Kudacki / AP

Police arrive on the scene of an explosion Saturday in Manhattan’s Chelsea neighborhood in New York. | Andres Kudacki / AP