A man is being treated for life-threatening injuries following a crash on the A14 in Cambridgeshire in which a driver failed to stop.
The man was in a silver Vauxhall Zafira which collided with a silver Audi at Stow Cum Quy at noon.
He was taken to Addenbrooke's Hospital in Cambridge, where his condition is described as stable.
Police said they are seeking the silver Audi, which they believe would have had "significant" front-end damage.
The car had alloy wheels and tinted windows.
Anyone with information is asked to contact police.