Police are yet to make any arrests for the armed robbery at Westport's Mill House Dairy on Sunday night.
Sergeant Malcolm Lamont said they were talking to a number of people and examining CCTV footage for evidence.
Three men armed with a gun held up a 17-year-old living at premises attached to the dairy late Sunday night and beat him.
The intruders stole cigarettes, tobacco, computers and other items before making off in the victim's car. The car was later found alight near the bottom of Alma Road.
Mr Lamont said the victim's brother was first on the scene of the burning car and managed to put the fire out with a fire extinguisher.