Police spokesman Allan Mullacrane said the girl was walking south of Guy Street about 7pm when she was approached by two men in a silver car.
The 16-year-old kept walking but the passenger then jumped out of the car, grabbed her and bundled her into the front seat of the car, which was similar to a Subaru.
They sped to the outskirts of the town via Guy Street and Ruahine Street before stopping in Umutaoroa Road, opposite number 58.
“The two men have then bundled the girl out of the car and over a wire fence into a nearby paddock, where she was sexually assaulted,” Mr Mullacrance said.
“They then left her in the paddock and the girl walked from there to a friends, at which point the police were called.”
Police wanted to hear from anyone who saw the four-door sedan, which has a dent in the rear bumper and with its back number plate on an angle.
The driver was Maori, of big build, about 1.8m tall and aged about 25. He was wearing a singlet and track pants. He had a spiral tattoo on right upper arm.
The passenger was Maori, of small build, with blue eyes. Both had their faces covered.