A teenager had to have part of his leg amputated after he was seriously injured in an explosion in Central Park Sunday.

Connor Golden, 18, of Fairfax County, Virginia, had to have his injured leg amputated below the knee, Golden's grandparents told NBC New York

Golden had stepped on a rock around 11 a.m. inside the park, near the area of Fifth Avenue and East 62nd Street. The explosion was reportedly caused by a homemade device or fireworks "experiment," Channel 4 reported. Investigators believe the explosive was left behind by an amateur or hobbyist.

Golden was with his friends, also visiting from Fairfax County. After the incident, a bag of fireworks was found nearby, but the group denied playing with them. Police now say they believe the device had been in the park for about a day.

Investigators also told Channel 4 that there was no evidence linking the explosion to terrorism.

Investigators said the object was likely fabricated by an amateur fireworks enthusiast for the thrill of creating a loud noise and flash. At least one bystander in the park told CNN the blast sounded "like a cannon."

The park remained open to visitors following the blast, but police were checking for any additional explosives in the park, using dogs trained to detect vapor trails left behind by explosives or would-be bombers.

Teams of so-called Vapor Wake Detection dogs were being deployed in New York for the first time as part of stepped-up measures to protect America's most populous city during the holiday weekend.

Reuters contributed to this report.