Police officials believe a homemade firework likely caused a blast in New York City’s Central Park that seriously injured a man who stepped on it.

The commanding officer of the New York Police Department’s bomb squad tells reporters 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 19-year-old or his friends took part in constructing the explosive. They’re asking anyone with information to come forward.

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

They say police dogs are canvassing the park for possible explosives.

(AP)