NEW YORK (AP) – New York City police said a 19-year-old man suffered a serious injury to his left foot in Central Park, and the man’s friends say he stepped on something that exploded.

Authorities said the man had been in the park at about 11 a.m. Sunday. Police said witnesses told them the man had just stepped onto a rock when an explosion occurred. Witnesses said an explosion was heard blocks away.

The Fire Department said the man sustained a major injury, possibly an amputation, and was taken to a hospital.

Authorities didn’t immediately identify the injured man.

The NYPD’s bomb squad and police were investigating.