A man is in a critical condition after seven vehicles came off the A66 in "appalling weather conditions" near the border of Cumbria and Durham.
The man, aged 22, who was from the Cockermouth area, suffered serious head injuries and was taken to hospital in Middlesbrough.
Six other vehicles came off the road at the same location at Stainmore summit, early on Monday.
Another man, from Sheffield, suffered a head injury.
He was taken to hospital in Darlington. A woman from Macclesfield was also taken to hospital with cuts and bruises.
The road was closed for five hours because the road was deemed impassable by police.
Police said drivers faced "appalling weather conditions" due to freezing fog and rain.
The road was made unsafe because of black ice.
Police are appealing for witnesses.