Three men were spotted fleeing in a car from the bank in Groß Leuthen, Brandenburg at around 2:20am by a nearby resident.
The entrance to the bank was seriously damaged, with the roof partly blown off and one wall fallen in, but police said the building was not in danger of collapse on Thursday morning.
Police were unable immediately to confirm whether any money had been stolen from the building, but forensic specialists from the state police were on the scene hunting for clues.
Neither could they confirm whether Michael Caine had been on the scene to rebuke the explosives specialist with his famous line from The Italian Job.
No-one was hurt in the explosion.
The raid is the latest in a series of blasts to hit banks across Germany, with several recorded in Brandenburg and in North Rhine-Westphalia.
But the robberies usually take place in banks close to an Autobahn so that the thieves can make a quick getaway.
State police in Düsseldorf said earlier this month that there had been several million euros' worth of damage and thefts in the series of heists.
Federal police said that there had been 63 explosive attacks on banks so far this year, compared with 116 in the whole of 2014.