Gardai in Letterkenny are investigating a robbery at the Dry Arch Petrol Station on the outskirts of the town.
At 2.35 this morning, two males entered the premises, produced a handgun, and escaped with what gardai are describing as a substantial quantity of cash.
Gardai say they made their getaway in dark coloured vehicle.
Gardai are appealing for information, and are urging anyone who may have seen anything suspicious in the area to contact them.
At present, gardai are examing CCTV footage as the investigation into the robbery continues.