Ontario's Special Investigations Unit has been called in after a single-vehicle crash that sent a 62-year-old man to hospital.

The collision happened on Sexton Road, northeast of Watford, around 4:30 p.m. on Thursday.

The SIU says a Lambton County OPP officer was conducting radar surveillance on Confederation Line when he began to follow a vehicle that had been speeding.

The vehicle turned north onto Sexton Road and shortly afterward crashed in a field just north of Zion Line.

Following the crash, the driver of the vehicle was airlifted to a London hospital, where he remains in critical condition.

The SIU has assigned three investigators and two forensic investigators to to look into the incident.

Anyone with information is asked to contact the lead investigator at 1-800-787-8529 Ext. 1898.