Nearly 1,000 extra state police and national guard troops will be deployed in New York as authorities vow to catch those behind a bomb attack in Manhattan.

At least 29 people were hurt in the explosion, which ripped through the busy neighbourhood of Chelsea on Saturday night.

The bombing has been called a terrorist act by officials, who say that so far there is no evidence of a connection to international terrorism.

Cuomo: Extra New York police after bombing

Police combing the area with sniffer dogs following the blast in the fashionable district also discovered a second suspected device nearby which had failed to detonate.

The New York Police department said on Sunday night it will carry out a controlled explosion of the second device at a police facility in the Bronx.


New York governor Andrew Cuomo said the extra officers will be placed at bus and subway stations as well as airports as a precaution.

Image: The suspect device found by police a few streets away from the blast

He vowed that whoever planted the devices would be found and brought to justice, but added there was "no reason to believe there is any further immediate threat".

Governor Cuomo said: "We're not going to let them win. We're not going to let them instill fear."

No individual or group has claimed responsibility for the bombing, which happened at about 8.30pm local time.

Blast CCTV: Debris rains down as people run for cover

It blew out the windows of nearby businesses and sent debris flying across the area.

Mr Cuomo said the explosion caused significant damage to properties and most of the injured were hit by glass or debris, but pointed out "we were very lucky there were no fatalities".

All the wounded who were taken to hospital were later released.

'All of a sudden we hear a boom'

Initial investigations suggest the Chelsea explosion, described as "deafening", occurred inside a large bin or a construction toolbox.

Pictures from the scene showed a twisted and crumpled black metal box.

The second device - a pressure cooker connected to a mobile phone with wires attached - had been placed in a plastic bag inside a bin.

Manhattan witness: I heard boom .... it was so huge

A piece of paper with writing on it was also found next to it, according to reports.

:: What clues are there for investigators?

It was later removed by bomb disposal teams using a remote-controlled robot.

Image: New Yorkers stand behind a police cordon following an explosion in the Chelsea district of Manhattan Image: At least 29 people were injured in what the authorities said was an intentional act Image: Police combed the area with sniffer dogs following the blast Image: A vehicle with a blown-out window seen on West 23rd Street Image: Emergency services discovered a suspect device nearby Image: Firefighters were quickly on the scene of the blast Image: NY police chief James O'Neill (R) and Mayor Bill de Blasio make their way to a news conference. Mr de Blasio ruled out any terror connection to the blast Image: Continue through for more images from the scene /

Pressure cookers packed with explosives and detonated with timing devices were used by two brothers in the 2013 Boston Marathon bombing that killed three people and wounded more than 260.

The security alert came just hours after a pipe bomb blast at a New Jersey charity run in aid of US Marines and sailors.

It is not believed the two attacks were linked.

Resident Neha Jain, 24, who was at home watching a film at the time, said of the Manhattan blast: "Pictures on my wall fell, the window curtain came flying as if there was a big gush of wind.

Image: Police take away what is believed to be the unexploded device

"Then we could smell smoke. We went downstairs to see what happened, and firemen immediately told us to go back."

Rudy Alcide, a nightclub bouncer, said: "It was extremely loud, almost like thunder, but louder."

Following the explosion, Facebook activated its safety check service that lets users notify friends and family that they are safe.

It was the first time it had been used in New York.

Presidential candidates react to New York blast

A Joint Terrorism Task Force, made up of different law enforcement agencies, has been called in to investigate, indicating the authorities have not ruled out the possibility of a terror link.

Surveillance video from businesses in the area will be examined by investigators hunting for clues to the explosion.

President Barack Obama has been "apprised" of the situation, according to a White House official.

The two presidential candidates have also responded to the explosion.

Debris seen at site of explosion in Manhattan

Democratic nominee Hillary Clinton said the nation needed to support its emergency workers and "pray for the victims".

She added: "We have to let this investigation unfold."

However, her Republican rival Donald Trump was more forthright, saying: "We better get very, very tough. It's a terrible thing that's going on in our world, in our country and we are going to get tough and smart and vigilant."

New York, which recently marked the 15th anniversary of the 9/11 terror attacks, is to host world leaders this week at a meeting of the United Nations.