A 75-year-old motorist tried to thwart knife-wielding car-jackers by refusing to hand over the keys to his vehicle.
West Midlands Police praised the bravery of the pensioner after releasing dash-cam footage showing his Ford S-Max being forced to a halt by a man standing in the road on Monday.
The victim stopped his car beneath a railway bridge in Roberts Road, Acocks Green, Birmingham, before being threatened with an imitation firearm and a large kitchen knife.
Local residents came to the aid of the pensioner, who was assaulted and pushed to the floor, after the offenders stalled the car on nearby Oxford Road and ran off.
A 17-year-old youth has been arrested on suspicion of robbery.
Appealing for information about a man captured on camera under the bridge, Detective Constable Tom Lyons said: "We're taking this incident extremely seriously and local officers will be patrolling the surrounding area, day and night.
"Clearly this would have been a terrifying ordeal for anyone and I want to commend the bravery of the victim.
"Thankfully he was not seriously injured and his actions prevented the thieves from successfully stealing the car.
"Although the arrest is a significant development we are still looking to identify a second suspect caught on the dash-cam footage from the vehicle."
Anyone with information is asked to contact Det Con Lyons at Stechford police station by calling 101 or emailing email@example.com.
Alternatively information can be given anonymously to Crimestoppers on 0800 555111.