CCTV images have been released after a man tried to rob a filling station in Gloucestershire.
Police received a report that a man with a knife had entered the Waitrose petrol station on Honeybourne Way, Cheltenham, on Wednesday.
He shouted for the till to be opened, but staff said they could not, the force spokesman said.
The man then left and headed towards the upper level of the supermarket's car park.
The incident happened at about 1520 GMT. No one was injured.
The suspect is described as white, aged in his early 20s, about 6ft tall, and slim.
He was wearing a black leather jacket and a hoodie and his face and head were covered.
A knife was later found a short distance from the petrol station.
Officers are appealing for witnesses.