Two teens were injured in what was described by police as a “serious crash” shortly before 2:25 a.m. Thursday just east of Waterloo.

The single-vehicle rollover occurred in the area of 5100 State Route 156 near Susewind Lane. Emergency radio dispatch communication indicated there was “thick fog” at the time of the crash.

Route 156 was closed to traffic in the area of the crash until about 6 a.m.

Responding agencies included the Monroe County Sheriff’s Department, Waterloo Police Department, Monroe County EMS and Waterloo Fire Department.

Monroe County Sheriff Neal Rohlfing said the driver was a 17-year-old who had been ejected from the vehicle and pinned underneath. She was extricated from the scene and transported by ambulance to Mercy Hospital South in St. Louis County for treatment of serious injuries. 

The passenger was a 13-year-old who was also transported to Mercy South for treatment of minor injuries. 

Rohlfing said an Illinois State Police accident reconstruction unit was requested and responded to the scene to assist with the crash investigation.