A pensioner who was fatally injured in a suspected road rage attack suffered "multiple stab wounds" when he was attacked by another motorist, police said.
Victim Donald Lock, 79, was stabbed by the younger motorist when their cars crashed on the A24 in Findon, West Sussex last night.
Sussex Police said a manhunt was under way for the suspect, aged 30-40, who later fled.
Mr Lock died at the scene.