A bungled attempt by five masked men to steal an ATM containing $641,000 in cash has been laid bare in official police reports, revealing a meticulously planned operation that unravelled after a stolen backhoe broke down at the crucial moment.

The reports detail how two security officers on duty at the Courland Beach Sports Arena were ambushed shortly before midnight on Wednesday by two men dressed in dark clothing, one armed with a firearm.

The guards were searched and ordered to hand over the keys to a white Mitsubishi truck and a yellow Caterpillar backhoe.