LONDON, ONT. -- The province's Special Investigations Unit (SIU) is looking into the circumstances of a collision Wednesday morning west of London.

According to Strathroy-Caradoc police, an officer tried to stop an Audi S4 around 9:30 a.m. for a Highway Traffic Act offence.

The driver sped off and crashed into a Toyota Corolla at Longwoods Road and Christina Road.

That's when the driver of the Audi took off on foot.

The lone 59-year-old female occupant of the Toyota had to be extricated by the Strathroy-Caradoc Fire Department and taken to hospital with serious injuries.

Three SIU investigators and two forensic investigators have been assigned to the case.

The intersection will be closed for several hours for the investigation and motorists should avoid the area.

Witnesses are asked to contact the SIU at 1800-787-8529.