The explosive that tore apart a tourist's leg in New York's Central Park Sunday morning was most likely a 'homemade' firework, police have announced.

Connor Golden, 18, had his left foot 'severely mutilated' when he stepped on something as he was climbing rocks with friends Thomas Hinds, 20, and Matthew Stabile, 18.

Despite fears that the explosive was a terrorist device, cops say it was more likely a pre-Independence Day 'experiment' by a chemistry enthusiast, and that the chances of Golden - or anyone - triggering the explosive were low.

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Tourist Connor Golden, 18, had his left foot mangled after accidentally jumping onto a 'homemade explosive' in New York's Central Park Sunday morning. Cops say the device was not made by terrorists, however

Golden, from Fairfax, Virginia, is seen be taken away from the scene by paramedics. Police say the device was most likely a homemade firework made by a chemistry enthusiast, and that Golden's injury was an accident

Golden was visiting from Fairfax, Virginia, with friends Thomas Hinds (right), 20, and Matthew Stabile (left), 18, when the horrifying incident unfolded

Hinds said that police questioned them intensively, asking whether they had been playing with firecrackers. Authorities concluded that the trio had nothing to do with the amateur device

Speaking at a press conference held in front of the rock where the explosion took place, NYPD Deputy Chief John O'Connell said that there was 'no evidence that (the explosion) was related to terrorism' and that there had been 'no credible threats against New York'.

These conclusions were preliminary, O'Connell warned, but police were confident in their beliefs.

The officer went on to say that it was 'not unusual' for people to experiment with homemade explosives and fireworks around July 4.

Cops believe the intent of the explosive's creator was just to 'make a loud noise, make a flash', he said.

The explosion occurred at 10.52am, when Golden leaped off the rock and landed on the device, which detonated, severely damaging his foot.

The fact that his two friends were unharmed, and that the damage was only to one leg, was evidence that it was not intended to harm anyone, O'Connell said.

It had been placed in an area where 'no-one would ordinarily step', he added, but told reporters that Golden and his friends were not involved in building the device.

Police believe it had been there for at least a day.

Bomb dogs were out looking for other devices in the area near where the explosion occurred

Golden (pictured) had been looking for areas to 'slackline' - a practice similar to tightrope-walking - on top of one of Central Park's boulders when he stepped onto the homemade explosive

Hinds (left) was about six feet ahead of Golden when the device went off. Stabile (right, with Golden and another pal) was behind and only saw dirt flying into the air. Hinds said Golden's foot was 'demolished' by the explosion

The device had been left in a rarely-used area of the park for at least a day before it exploded, police said. They don't believe it was designed to be detonated on impact, but did so because it was made of unstable chemicals

Preliminary analysis by the NYPD bomb squad suggests that the device was not pressure sensitive, but that it was made of 'homemade material' that was sensitive to blows.

Another source told NY Post that the 'tiny' device had been contained in a brown bag and was surrounded by wet matches.

A bomb squad expert said that building such a device would require a good knowledge of chemistry - but nothing that couldn't be gleaned from an internet search.

Police are continuing to look for further evidence, and are appealing for witnesses and video of the area.

Golden, who was visiting New York from Fairfax, Virginia, was seen being treated at the scene with his bloodied foot heavily bandaged; in another, his toes can be seen pointing in the wrong direction.

He is currently undergoing surgery at Bellevue Hospital and his condition is described as 'stable', FDNY Deputy Assistant Chief Michael Gala said.

Golden and his friends did not build the device, police said. He is undergoing surgery in Bellevue Hospital, and is said to be in 'stable condition'

The explosion occurred near the Fifth Avenue and East 62nd Street area, a short distance away from the Central Park Zoo.

The boys - who arrived in New York on Saturday evening - were climbing over the large boulders that dot the park when the horrific accident occurred.

Hinds told the NY Post that they were looking for places to 'slackline' - a practice similar to tightrope walking - when the device went off.

Golden was in the middle of the three as they dismounted a rock, Hinds said.

'I got down the hill and boom, my ears were ringing. I felt a wave, a gust hit me in the back,' Hinds told NY Daily News. 'I turned around and saw him on the ground with his foot bleeding.

'It just demolished his foot.'

But Hinds said Golden 'handled it pretty well.' 'He's a tough guy,' he added. 'All he said was, "Get help."'

'My understanding, I could be wrong, is he’s in surgery right now and they are hoping to keep his foot,' Hinds told ABC.

Police questioned Hinds and Stabile separately, he said, adding that they 'were understandably going at us hard asking about firecrackers, because the idea that there would be some sort of bomb in Central Park is really scary.'

He was taken to New York's Bellevue Hospital alongside his two friends for treatment

Witness John Murphy, 53, a tourist from Connecticut, told the New York Daily News he tried to keep the young man conscious following the explosion.

'The friends were just in shock,' he told the NY Post. 'He was severely injured. His left leg was severely damaged, all bone and muscle.'

Hinds added: 'At first, I thought we were being attacked,' he said. 'It was a very loud explosion, and I couldn’t help but think of all the stuff in the news. That’s just what your mind automatically jumps to.

'But when I turned around and saw that [Connor] had stepped on something and was hurt, I went into shock. I realized that that could’ve been me. I went ahead first and the place where he stepped was inches away from where I was walking.'

Murphy said Golden had managed to stay awake until paramedics arrived. 'He was an absolute trouper,' he said.

'I couldn’t believe it. We just stayed with him, tried to keep him calm until EMS showed up. He was in shock. I don’t think he even realized what had happened.'

'Connor is a really laid-back guy who really likes music and the outdoors,' Hinds told the New York Post. 'We love to go camping together, so on the fifth day of our trip, we were gonna head upstate to the Adirondacks for the weekend and then head home.

'But that’s all changed. Now, I just hope they can put his foot back together.'

The blast was close to where the funeral for Holocaust survivor and Nobel winner Eli Wiesel was taking place on Sunday morning

The explosion went off near to where the funeral for Holocaust survivor and Nobel winner Eli Wiesel was taking place on Sunday morning.

But there is nothing to suggest the blast was related to the service.

New York Times reporter Sarah Maslin Nir Tweeted at the time: 'Outside Eli Wiesel's funeral I heard a huge explosion just now. Running into Central Park and found a young man with his left leg blown off.'

She later added: 'The young man is safely on his way to hospital. No official word as to what transpired. His friends said he was walking & stepped on something.

'Possible fireworks accident or other cause, no word on cause as this happened moments ago.'

The explosion occurred close to where the funeral of Holocaust survivor Eli Wiesel was occurring, but authorities have said the two events were completely unconnected

First responders are seen wheeling a stretcher into the area where the blast took place

The explosion occurred near the Fifth Avenue and East 62nd Street area. It is an area heavy with tourists and a short distance away from the Central Park Zoo

Paramedics are seen taking Golden into the back of an ambulance near the scene

Parts of the park were closed off after the explosion

NYPD cops are seen in a closed-off section of Central Park as they investigate the explosion