Officers are searching for a suspect who likely fired on the festivities from a rooftop, police said Monday.

Highland Park Police Commander Chris O’Neill, the incident commander on scene, urged people to shelter in place as authorities search for the suspect.

Lake County Major Crime Task Force spokesman Christopher Covelli said at a news conference that the gunman apparently opened fire on parade-goers from a rooftop using a rifle that was recovered at the scene. He didn’t know which building.

Covelli said police believe there was only one shooter and warned that he should still be considered armed and dangerous. He and O’Neill described the shooting as random. — Agencies