Three drivers had a shocking surprise while innocently driving along the A30 on Sunday, after police accidentally dropped a 'stinger' into the the path of oncoming traffic.
Three cars had their tyres burst by the device, which fell out of the boot of a police car while officers were attending a crash near Launceston.
In total five tyres were destroyed, leaving the drivers sitting at the side of the road until they could be replaced, with one not to happy about the six hours he lost dealing with the issue.
Taxi driver John Beach said he was left for two hours in cold waiting for the RAC to recover his car after the mistake, adding that police then sent a tyre firm around to his home to replace the tyres at around midnight.
John lost one rear tyre after hitting the 'stinger' while on a trip back to Cornwall from Bristol, adding that the two other cars lost two tyres each.
"They [police] knew straight away it was their fault," said John. Adding it was a bit of shock.
The 'stingers' have long metal barbs, teeth or spikes pointing upward which puncture and flatten tires when a vehicle is driven over them.
Devon and Cornwall police have apologised to the drivers.
A police spokesman said: "At approximately 5:45pm on Sunday, February 16 a single vehicle collision occurred on the A30 at Tregadillett near to Launceston.
"A police unit attended the scene to assist with traffic management. While placing emergency signage at the scene, the stinger device fell from the boot of a police vehicle.
"The device was immediately run over by three vehicles, leaving five tyres damaged.
"None of the drivers were injured and the force ensured that all damaged tyres were replaced by a professional roadside tyre replacement service at the scene.
"We apologise for any inconvenience and distress caused to the drivers as a result of this unfortunate incident.