A woman has died and several people have been injured in four accidents on the A40 in Oxfordshire.
Up to 20 cars have been involved in the collisions. Roads are closed between Witney and Burford Road.
A pregnant mother from Oxfordshire who was a passenger in a car on the A40 has described the moment she saw the first vehicle crash.
Ami Gaston, from Carterton, says she was in the car with her partner when she saw the accident happen about half a mile from the Witney exit, blocking the right lane.
She said: "A man on his own had skidded and crashed into middle barrier. My partner was driving - we had to swerve out of the right lane to avoid hitting him. His door was open and air bags were released," Miss Gaston said.
"I phoned an ambulance but couldn't stop. My partner wouldn't stop because I am 20 weeks pregnant and didn't want to put us in danger."
She added that the heavy fog meant the situation was "really dangerous", as it was difficult to see any other car until you were "on top of it".
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