Graphic photos of 18 year-old tourist's leg blown off by homemade explosive hidden among the rocks in Central Park

The explosive that ripped up a tourist's leg in New York's Central Park Sunday morning was most likely a 'homemade' firework or other explosive device, 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.

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.