JOLIET, Ill. (AP) — A suburban Chicago police officer faces a drunken driving charge after she was involved in a traffic collision in which an officer from another department riding with her was killed.

Illinois State Police say Joliet Police Officer Erin Zilka was driving in Will County on Interstate 55 early Sunday when her vehicle slammed into a truck that had been involved in a crash a short time earlier.

Berwyn Police Officer Charles Schauer, a passenger in Zilka’s vehicle, was pronounced dead at the scene. Joliet Police, where Zilka has been an officer for 12 years, says it has launched an internal investigation.