Gardaí said the white Ford Transit van was being used to make deliveries to businesses in Ballydehob village when it was stolen at around 9.50am yesterday morning.
It was taken by a 47-year-old man who drove it along the N71 to Skibbereen, where it was involved in a collision with a Suzuki jeep whose occupants were an 80-year-old man and his wife.
The van driver failed to stop at the scene and was later apprehended by gardaí from Skibbereen.
The man was arrested and taken to Bandon Garda Station. He was being questioned about the unauthorised taking of a vehicle.
Superintendent Pat Maher, who is leading the investigation, said that the 80-year-old man, who is from Glengarriff, sustained serious injuries in the crash and was rushed to Cork University Hospital.
His wife suffered minor injuries and was treated at a local doctor’s surgery.
The hit and run occurred near Abbeystrewery cemetery, about a mile from Skibbereen town centre, just before 10.30am. The road was closed for a number of hours yesterday as Garda Forensic Collision Investigators examined the scene.
Superintendent Maher said gardaí were appealing for anybody who may have seen the van driving erratically or dangerously along the 10-mile stretch of road between Ballydehob and Skibbereen. The van had a 02-C registration.
* Information to Skibbereen Garda Station at 028 23088, or Clonakilty Garda Station at 023 8821570.