Police arrested a male and female, both aged 18, early yesterday morning, and are continuing the search for a third teen involved in the incident.

Police said the alleged assault happened at around 12.30am on Thursday, when two males and a female aged between 18 and 19 drove to a car park in Katherine.

"They allegedly confronted a 15-year-old female and an 18-year-old male," a NT Police spokeswoman said.

"The 19-year-old male allegedly threatened the victims with a bow-and-arrow before releasing a dog which attacked the 18-year-old male victim.

"The 15-year-old female victim was also assaulted."

Police say the group of three left the scene and two of them were located and arrested by Katherine Police a short time later.

"Police continue to search for the outstanding 19-year-old male allegedly involved with this incident," the spokeswoman said.

The 18-year-old victim allegedly attacked by the dog was taken to Katherine Hospital where he received medical treatment for injuries.

Residents are being urged to contact police with information on 131 444 or anonymously via Crime Stoppers on 1800 333 000.

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