A 16-year-old boy has been charged with murder after a Chicago police officer fatally shot his 15-year-old friend Wednesday on the South Side.

Brandon Ross and his friend Tatioun Williams allegedly robbed a man at gunpoint in the 7000 block of South Cregier Avenue Wednesday evening, and were confronted by police officers a short time later, the Chicago Tribune reports.

When the officers told the teens to stop, Williams, who was holding the gun, allegedly turned in the officer's direction, Fox Chicago reports. Fearing for her life, the officer shot the 15-year-old, killing him.

"They could have taken him to jail, they could have done anything but taken his life," Williams' mother told the Tribune Thursday.

Under state law, police can charge someone with murder when an accomplice is killed during the commission of a crime. Even though Ross didn't pull the trigger, he was charged as an adult with murder and armed robbery. He was ordered held on $900,000 bail Friday.

The teens allegedly took a wallet and iPod from a 27-year-old man before the shooting.