Three people were seriously hurt in an ATV rollover west of St. Thomas.
The machine overturned on John Wise Line, south of Blind Line in Southwold Township around 8:10 p.m. on Sunday.
Elgin OPP, Southwold firefighters, and paramedics responded to the crash.
A 36-year-old from Southwold, a 58-year-old from Brantford, and 51-year-old from Rosslyn were taken to hospital with serious injuries, police said.
The OPP west region traffic incident management and enforcement team continue to investigate the cause of the collision.
John Wise Line between Talbot Line and Fingal Line was closed for several hours while investigators were on scene.
Anyone with information about the crash is asked to call police at 1-888-310-1122 or Crime Stoppers at 1-800-222-84777 (TIPS).
