NEW YORK (CBSNewYork) — A firework that exploded when a 18-year-old unwittingly stepped on it Sunday in Central Park, seriously injuring his left foot, didn’t appear to be designed to intentionally hurt people, police officials said.

WCBS 880’s Sophia Hall reported the victim, identified at Connor Golden, suffered a severe leg injury. The explosion happened just before 11 a.m. near 60th Street and 5th Avenue.

WCBS's Sophia Hall heard explosion in Central Park. One victim with injured leg/foot being treated by EMS. — Alex Silverman (@AlexSilverman) July 3, 2016

WCBS 880 reported that Golden was with a group of three young men from the Washington, D.C. area.

“I don’t know what happened. I don’t know what happened,” one of the men told WCBS 880.

An eyewitness told CBS2 that Golden was climbing a rock structure and stepped on something that “exploded.”

Police officials believe a homemade firework likely caused the blast, CBS2’s Hazel Sanchez reported. The commanding officer of the New York Police Department’s bomb squad said Sunday there’s no indication it was made to harm people.

Mark Torre likened the explosive to an experiment that an enthusiast with a rudimentary understanding of chemistry could build from household materials.

Investigators don’t believe the injured 18-year-old or his friends took part in constructing the explosive. They’re asking anyone with information to come forward.

Officials say Golden is undergoing surgery on his left foot at a hospital. He’s in stable condition.

#CentralPark scene has started to thin out. Preliminary reports: #Fireworks likely a cause of the small explosion @CBSNewYork — Magdalena Doris (@MagdalenaDoris) July 3, 2016

A bomb-sniffing dog went into the rock area where the explosion took place.

#BREAKING: Explosion in Central Park injures man on rocks after landing on something that blew up @CBSNewYork pic.twitter.com/tNhIp3gQuz — Magdalena Doris (@MagdalenaDoris) July 3, 2016

CBS2 video captured the sound of the explosion while guests were filing into Elie Wiesel’s funeral in the Upper East Side.

Mayor Bill de Blasio tweeted: “Dangerous incident in Central Park today. Fireworks are fun – but let’s leave them to the professionals. Stay safe.”