The province's police watchdog says a woman's arm was severed during a pursuit on Highway 401 in Napanee this morning.

The Special Investigations Unit says officers stopped a car and began the pursuit after the driver fled the scene.

The car rolled over in the area of Switzerville Road and the 21-year-old driver was taken to Kingston General Hospital for treatment of a severed arm.

The SIU has assigned three investigators and two forensic investigators to probe the circumstances of the incident.

The SIU investigates reports involving police where there has been death, serious injury or allegations of sexual assault.