Six arrests have been made in connection with a series of explosive heists against cash machines in recent months, which German police have linked to organized gangs. Three Dutch men aged between 19 and 25 have been arrested in the western German state of Lower Saxony, Frank Federau, a state police spokesman, said on Sunday. The trio became known to police when they were seen driving in a car flagged as one of the getaway vehicles. Federau did not give further details on the charges against the three Dutch men. Another three arrests were made in the neighboring state of North Rhine Westphalia after robbers attempted to blow up 13 cash machines without success on Thursday. Investigators in that state have placed the costs of these explosions at around 4 million euros (4.4 million dollars). Federau said that bands of cash machine raiders are active across Germany. According to witnesses, the criminals tend to strike between 2 and 5 am, with some attacks occurring within minutes of one another. The crimes are heralded with a bang loud enough to crack nearby windows, usually followed by the screech of tyres as the bandits flee the scene, dpa reported.