Waterloo police are investigating a shooting incident that left the driver of a vehicle dead and a passenger injured early Sunday.

According to a press release, authorities were called to U.S. Highway 218 near the Cedar River bridge around 2:30 AM. When they arrived, officers found a vehicle on the southbound shoulder of the Greenhill Road off ramp, with three adults inside.

Police said it appears a single bullet struck the vehicle as it was going south, entering Waterloo. The bullet entered the vehicle and struck two of the three occupants, killing a woman and injuring a man.

According to police, the female driver died at the scene. The male passenger was taken to UnityPoint-Allen Hospital in Waterloo for treatment, then transferred to University of Iowa Hospitals and Clinics in Iowa City. The other passenger wasn't injured. Their identities weren't immediately released.

As part of the investigation, authorities closed U.S. 218 for several hours following the incident. The Iowa Department of Transportation reported the highway was reopened around 7:30 AM.

Police are asking for the public's help in the active investigation. Anyone with information about the case should contact Waterloo police.