A 34-year-old driver began having a fit after being punched by another motorist when they both left their vehicles in Cookstown on Saturday.
Police were called to the scene at Orritor Street in the Co Tyrone town by parademics at 4.45pm.
A PSNI spokesman said it was understood the driver of a black Audi A4 punched the victim, who was driving a silver Vauxhall Vectra, which caused him to lose consciousness and subsequently take a fit.
The spokesman said the alleged assailant left the scene prior to the arrival of the emergency services.
Witnesses are asked to contact 101.