A gang of robbers dug a tunnel to enter Al Baraka Bank in South Africa's main city, Johannesburg, in the early hours of Wednesday morning.
However, the attempt to rob the bank failed because the alarm went off and the gang fled, the bank's chief operating officer, Mohammed Kaka, was quoted by the local News24 site as saying.
Police have still not caught the robbers.
South Africa has one of the highest rates of crime in the world.
Gunmen have hijacked armoured vehicles transporting large sums of money, and have also blown up cash machines.