Police are investigating an armed robbery incident that occurred at Marlborough this morning (December 5).

At about 7.05am at a petrol station on the Bruce Highway, three male persons have attended the business, threatened staff with a gun and demanded cash.

The three males then left the business with a quantity of cash in a white four wheel drive vehicle.

A short time later the vehicle was located on fire in Glenprairie Road.

At about 8am, one of the males was intercepted in a vehicle at Yamba and taken into custody.

At about 11.20am, police located the remaining two men who were on foot in the Yamba area who were also taken into custody.

An 18-year-old-man, a 17-year-old-man and a 15-year-old boy are currently assisting police with their inquiries.

Investigations are continuing.