NT Police are investigating a serious pedestrian crash on the Stuart Highway at Coolalinga that left one man with a broken pelvis and internal injuries and another with a broken arm, after they were struck at high speed by a car.

Police said a 29-year-old woman hit the two men around 7:40pm Monday evening on the right hand lane while driving toward Palmerston in a 100km/h zone.

The driver contacted police and stayed at the scene, later testing negative for dugs and alcohol, police said.

A 39-year-old man was found with a broken pelvis and arm, as well as a compound fracture to his leg and internal injuries and was taken to hospital for surgery on Monday night.

A 33-year-old man reportedly left the scene but was later discovered with a cut right arm which police said was also broken.

The vehicle was seized as part of the investigation but police said it was too early to determine if charges would be laid.