A group of youths who allegedly assaulted a service station employee and tried to steal items from the Stuart Highway store in Parap came back later in the night to threaten the assaulted staffer with a knife, NT Police said.

Seven youths had entered the service station around 10:15pm Tuesday where they attempted to steal before allegedly assaulting the worker and fleeing the scene, police said.

A group of five later returned with one of them brandishing an “edged weapon” to threaten the worker before again fleeing the scene.

Four females were arrested this morning, police said, aged between 12 and 14, and were expected to be charged later.

Police are seeking the other youths involved in the crime.

“This behaviour is completely unacceptable and we are urging anyone who witnessed the incident, or who has information, to make contact on 131 444,” Detective Senior Sergeant Mark Bland said. “Please quote reference 10022129.”