A man drove a police car around a car park with its siren on after two officers left it unattended with the keys inside.
The incident in Hampton, Peterborough on 4 July, was filmed and posted online.
Cambridgeshire Police said the man was given “words of advice” after he apologised to the officers, who had gone to get refreshments from a nearby shop.
A spokeswoman said: “Upon returning to the station, the officers promptly alerted a supervisor and admitted their wrongdoing.
“They were given management words of advice. It was clear an honest mistake had been made.”