The man was calm and softly spoken.
Detective Sergeant Jonathan Tier said the two attendants have been left severely traumatised after the aggravated robbery.
"Police need to apprehend this man to prevent any further violent crimes by him and before anyone is seriously injured," Mr Tier said.
He said the two attendants had been offered victim support.
The man was driving a stolen vehicle, a silver coloured Land Rover Discovery with the personalised plates DISC03.
The vehicle, which was stolen from Maunu last week, was located in Dargaville High School's carpark yesterday morning.
Mr Tier said some of the clothing worn by the man was found in the back of the vehicle.
Police are keen to speak to anyone who was near the Caltex service station at the time of the robbery, anyone who may have information that could help identify the man or who had seen the vehicle around Montgomery Ave in Dargaville.
This is the latest in a spate of robberies targeting cigarettes in Northland.
On August 19, three men wearing disguises entered Price Cutter in Kaitaia armed with weapons, including a knife and a screwdriver, and demanded money and cigarettes.
They got away with an undisclosed amount of cash.
On the same day, a man wearing a bandana and sunglasses entered Super Liquor on Three Mile Bush Rd in Kamo and pulled a weapon similar to a small hatchet.
He threatened staff and two customers before fleeing with cash and cigarettes.
On August 27, five youths pointed a gun at staff at Waipapa BP and stole tobacco, the cash drawer and chocolate.
Just over a week later, on September 4, a stolen car was used in a ram-raid of The Korna Shop in Morningside, where cigarettes and cash were also stolen.
Anyone with information relating to the aggravated robbery of Dargaville Caltex can contact Mr Tier at Dargaville CIB on 09 439 3400 or anonymously to Crimestoppers on 0800 555 111.