Theives got away with RD$3,516,000 in cash when they broke into a branch of the BHD bank in the Quisqueya area of Santo Domingo.
The armed security guard, Manolo Quevedo Montero was later found tied up and asleep, apparently drugged by the gang.
Police have yet to catch the criminals, although from initial investigations, it seems that they broke in around 10pm and spent the whole night in the bank, finally leaving at around 4am the next morning with the cash.
Police are not sure why they spent so long in the bank, although it seems they were able to disable the electricity, alarm and camera systems and cut through into the bank vault using acetylene torches.
Quevedo was taken in for questioning.