Three people wearing balaclavas and armed with unspecified weapons robbed a Katherine service station, NT Police said.

NT government crime marketing manager Sita Bacher said in a statement that about 5am Thursday three people entered the service station on the Victoria Highway, Katherine, wearing balaclavas and armed with weapons which were not specified by police.

Ms Bacher said the offenders demanded money from staff but a member of the public intervened, and the offenders left. It was not made clear if any money was taken.

Police are asking the public with information that may assist in identifying the offenders to call them on 131 444, or anonymously to Crime Stoppers on 1800 333 000.