Two men armed with a crowbar and sledge hammer attacked security guards delivering money to a cash machine at a Lancashire bank.
The masked robbers then smashed their way into the Abbey Santander bank in Burnley Road, Padiham, at 2315 BST on Tuesday.
They fled with cash in a grey saloon car, in the direction of Burnley.
The security guards were not injured in the raid, a police spokesman said.
Both robbers were white. One was wearing a black trousers with a white stripe, and carrying a black bag.
Police have appealed to anyone with any information to contact them.