A man is loaded into an ambulance after he was injured in an explosion in Central Park. (Reuters)

Officials believe an “explosive hobbyist” may have left behind the device that detonated when an 18-year-old man’s foot landed on it in New York’s Central Park on Sunday morning, creating a blast that resulted in a severe leg injury for the man.

Connor Golden was in surgery at Bellevue Hospital on Sunday evening with a grisly left leg wound that authorities said earlier in the day could require “possible amputation.” Officials said there was no evidence the incident was terror-related, and the working theory revolved around a person testing explosives, perhaps in advance of the Fourth of July holiday.

“We believe this could have been put here as some sort of experiment,” NYPD Inspector John O’Connell said during a news conference.

O’Connell and bomb squad commander Lt. Mark Torre said it was not unusual for individuals to create “homemade” fireworks as Independence Day celebrations approached. Officials were scouring the park for other, similar devices, but there was no evidence more than one existed.

Authorities appeared to cast doubt on any nefarious motives. O’Connell said the explosive was not placed in a location “where somebody ordinarily would have stepped,” and Torre said investigators hadn’t found any evidence to show the device was a “constructive IED.”

“There is some forensic evidence that indicates it was not meant to go off with somebody stepping on it,” said Torre, who noted he had not seen a similar incident dating back to 1993. “It may have not gone off at an earlier time and was just left there.”

Torre said the device, which was not described, had likely been in the park “longer than a day” and could have been constructed by someone with a basic knowledge of chemistry and access to a computer.

Golden and the two friends who were with him are not suspected of planting the device, O’Connell said.

Golden and his friends were visiting New York from Washington D.C. for the Fourth of July holiday, The New York Post reported. The trio was jumping from a large, sloping rock in the park at 10:52 a.m. when Golden’s foot triggered the device.

A witness, John Murphy, said Golden’s foot was “all but gone.” He said he spoke with Golden’s friends after the blast.

“I said, ‘Come on, guys, were you carrying fireworks?’ And they said no. And I believed them,” Murphy told The New York Post. “That was no normal firework. This wasn’t an M80 or a cherry bomb. Some something much more serious. I saw a diver that reminded me of impact craters.”

The incident, near Fifth Avenue and 68th Street, happened just a few blocks from where a funeral was being held for Pulitzer Prize-winning author Elie Wiesel and was also near the Central Park Zoo.