Eight people have been killed and around a dozen more seriously injured in a “particularly cowardly act of terrorism” after a rented truck ploughed through people on a bike path in lower Manhattan.

Bikes were strewn along the path, which runs alongside the West Side highway in Manhattan, after the attack, which is being investigated by the Joint Terrorism Task Force. It was the first fatal terror attack in New York since 9/11.

New York Police Department (NYPD) released an image of the suspected attacker, named as Sayfullo Saipov, 29. The Uzbek national, now in custody, is reported to have left a note pledging allegiance to Isis in or near the truck.

Mr Saipov, of Tampa, Florida, is said to have entered the US legally in 2010.

The truck entered the bike path at Houston Street, and drove through the popular recreational area on the west side of Manhattan, hitting people and bikes as it went, officials said. Estimates for the number of injured ranged from 11 to 15.

“I saw a lot of blood over there. A lot of people on the ground,” said Chen Yi, an Uber driver.

After careening through the cycle track, the truck was crashed into a school bus, injuring a number of people including children. The attacker then got out and brandished what authorities said was a paintball gun and a pellet gun. He was shot in the stomach and taken to a local hospital, and is expected to survive.

Witnesses indicated they had seen the truck swerve to hit the bus.

New York City Mayor Bill DeBlasio said: “This was an act of terror, and a particularly cowardly act of terror aimed at innocent civilians, aimed at people going about their lives who had no idea what was about to hit them.”

Sayfullo Saipov (St. Charles County Department of Corrections/KMOV/AP)

While no terror group has yet laid claim to the attack, New York and other cities around the globe have been on high alert against attacks by extremists in vehicles.

Isis has released detailed instructions on carrying out vehicle attacks while intensifying calls for global atrocities as its territories shrink in Syria and Iraq.

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The first terror attack using a lorry came in Nice, where an Isis supporter killed 86 people in July 2016.

Vehicles have since been used in attacks in Berlin, Stockholm, London, Paris, Spain and the Canadian city of Edmonton.

Isis has released several rounds of instructions on how to use vehicles in deadly rampages, stipulating what kind to use and how to hire or steal them.

The group’s propaganda has cited pedestrianised areas and crowded streets as prime targets after declaring murdering civilians “halal”, meaning permissible under Islam.

Most attackers then attempt to achieve “martyrdom” by being killed by security forces.

New York Governor Andrew Cuomo called Tuesday’s atrocity a “lone wolf” attack and said there was no evidence to suggest it was part of a wider plot.

New York City Police Commissioner James O’Neill said a statement the driver made as he got out of the truck and the method of attack led police to conclude it was a terrorist act.

On Twitter, President Donald Trump called it “another attack by a very sick and deranged person” and declared, “NOT IN THE U.S.A.”

“We know that this action was intended to break our spirit, but we also know that New Yorkers are Strong, New Yorkers are resilient,” Mr DeBlasio said. “We have been tested before as a city, very near where this attack occured.”

Police advised people to stay away from the area, which is around the Chambers Street. Reports indicate that a nearby high school, Stuyvesant High School, has been placed on lock down, as have several nearby buildings.

New York City will see an increased police presence in its airports, and at major infrastructure points in the coming day, Mr Cuomo said during a press conference. He said that there the city would be increasing security as a regular precaution.

Despite no claim for the attack having been made, Mr Trump also tweeted: “We must not allow ISIS to return, or enter, our country after defeating them in the Middle East and elsewhere. Enough!”

We must not allow ISIS to return, or enter, our country after defeating them in the Middle East and elsewhere. Enough! — Donald J. Trump (@realDonaldTrump) October 31, 2017

Witnesses in the area described a chaotic scene.

“There are nonstop sirens from here to at least Murray HIll,” Liz Shi, who was in the area but did not immediately witness the attack, said, referencing a Manhattan neighbourhood in Midtown.

Students at nearby Brooklyn Community College (BMCC) said that they felt lucky to have avoided the attack, and that even a slight change in the time could have made them a victim.

“I’m just thanking god this incident didn’t happen during my class, because I would have been that area; on that side,” Alex Johnson, a student, said.

“It’s Halloween. Today is the day where people are supposed to be out trick-or-treating. People have their kids out. There are schools all around here,” Mr Johnson said. “I thought this space was heavily guarded. It’s a wake-up call to know that anything can happen at any moment, and you just have to be aware of your surroundings.”

Jake Saunders, another BMCC student, said he had narrowly missed his the first train to campus. He took the next train a few minutes later, and got off at his usual stop – at the heart of where the attack had occurred, just minutes before.

“I saw people running away, cops pushing people away, crime scene tape being put up," Mr Saunders said. "I saw the FBI show up. I saw a stretcher being rolled out … [and] a crap-ton of ambulances rolling toward the scene – there must have been like 10. That’s when it hit me like, ‘Wait, what is happening?’”

He added: “I was very close to being right there when it happened. If I had made that train I could be dead right now.”

The bike path where the attack occurred sits in lower Manhattan, just north of the World Trade Centre, the site of the last major terrorist attack in the city. The path is lined with colourful autumnal trees, and runs near several schools including BMCC and a nearby high school.

The area also sees moderately heavy foot traffic, and had been teeming with children dressed for Halloween festivities.

A planned Halloween parade went ahead as planned, with defiant revellers saying they refused to let the attack keep them from their normal lives.