A 13-year-old boy was fatally shot Saturday afternoon when a gun was accidentally discharged in the Englewood neighborhood on the South Side.

Deon Williams and his teenage friend were playing with a gun about 3 p.m. in the 7300 block of South Aberdeen when it was fired, Chicago police and the Cook County medical examiner’s office said.

Williams was shot in his head and taken to Comer Children’s Hospital, where he died at 3:54 p.m., police said.

It was unclear who was holding the gun at the time, police said. No one is in custody.

The results of Williams’ autopsy were pending on Sunday, the medical examiner’s office said. He lived in the same block where the accident occurred.

Area South detectives are investigating.