Authorities say three teenagers, including a 13-year-old, have been killed in a shooting on Chicago's South Side.

Police Sgt. Antoinette Ursitti says the other victims were 14 and 17 years old.

The shooting occurred Friday afternoon in an alley located about a block away from Immaculate Conception School. It's not clear if any of the victims were students there. Their identities haven't been released.

Authorities say one of the victims died at the scene. The two others died after being transported to the University of Chicago Comer Children's Hospital and Advocate Christ Medical Center in Oak Lawn.

Chicago Police spokeswoman Officer JoAnn Taylor says the incident is under investigation. She says no one is in custody.