A man armed with an assault rifle is wanted in the killing of three people early Saturday on a party bus in Rockford.

Authorities are searching for the accused shooter, 22-year-old Raheem D. King, according to the Rockford Police Department. An arrest warrant has been issued for King, who is charged with four counts of first-degree murder and will be held with no bail if and when he is arrested.

Raheem D. King | Rockford police

Officers responding to a call of people shot about 3:30 a.m. found three people killed inside a private limousine-style bus in the 400 block of North Springfield, police said. The identities of the three slain haven’t yet been released.

Police said the shooter, who was a passenger on the bus, had opened fire with an assault rifle near Auburn Street and North Johnston Avenue. The passengers ran away after the attack, but the driver stayed on the bus and drove to Springfield Avenue before calling 911.

King, identified as the shooter, is considered armed and dangerous and is believed to still be in possession of an assault rifle, police said.

Anyone with information about his whereabouts was asked to call the Rockford Police Department at (779) 500-6551 or Crime Stoppers at (815) 963-7867.