Two men wearing balaclavas and holding an axe and an angle grinder broke into a Hampshire bank and stole money from two couriers emptying a cash machine.
It happened at the Nationwide in Park Parade, Havant, on Friday night.
The men took four cassettes "containing a substantial sum of money" from the couriers, said police. The G4S staff sustained minor injuries.
Officers said they could not say if the robbery was linked to a raid at an HSBC in Chandler's Ford on Thursday.
The robbers used a black VW Golf to drive away from the bank, which was believed to have been displaying number-plates stolen from another car.
Police are still looking for the Golf.