A man has died in a car fire on the M180 motorway in North Lincolnshire.
The vehicle caught fire on the hard shoulder of the westbound carriageway, between junctions four and three, at about 1150 BST.
Police said the man, who was alone in the car, had not been identified but was thought to be from Lincolnshire.
The case has been referred to the police watchdog because the car was being followed by officers shortly before the incident.
A Humberside Police spokesman said: "At this time the circumstances surrounding how the car came to be on the hard shoulder and set alight remains unclear and officers are currently trying to establish that.
"Lincolnshire Police have voluntarily referred the case to the Independent Police Complaints Commission (IPCC) because shortly before the incident the vehicle had been followed by a Lincolnshire patrol car."
An IPCC spokeswoman said: "Lincolnshire Police have informed the IPCC about an incident on the M180 earlier today.
"IPCC investigators have been deployed to carry out an assessment and a decision on our level of involvement will be made in due course."