Two masked robbers armed with a sledge hammer held up security guards who were delivering cash to a bank in Hampshire.
The raiders targeted the two Group 4 Security workers at the Farnborough branch of Santander in Eastmead on Monday evening, police said.
One of the guards was assaulted before the robbers escaped with what police described as a "quantity of cash" in a white car, thought to be a Vauxhall.
Police said the car may have been in collision with a white Audi as it left.
Detectives are appealing to the driver of the Audi to contact them.
Anyone else with information about the robbery, which occurred at about 22:00 GMT, is asked to contact Hampshire Constabulary.