One arrested, at least two on the run after offenders flee police, violently carjack motorists at gunpoint near Palmerston North

One person has head injuries and at least two offenders are on the run after a police chase and reported armed carjacking near Palmerston North.

Manawatū Area Commander Philip Ward said the situation unfolded just before 7:30am on Friday, after police received reports of a vehicle travelling fast on State Highway 57 at Aokautere.

The driver failed to stop when signalled by officers. However, Ward said the officers didn't pursue the vehicle.

About 10 minutes later, the vehicle was spiked near Ashhurst and officers began following it while driving to the speed limit.

The driver then stopped on State Highway 3 near Hacketts Rd, with the officers still about 1km behind.

Reports were then received the vehicle's occupants, one of whom appeared to be armed, had stopped traffic on the highway and stole two cars from innocent motorists, Ward said. 

"The victims who had their vehicles taken were shaken and one has been treated for a head wound.

"Given the immediate threat to the public, a pursuit was then authorised."

Ward said officers began pursuing one of the stolen vehicles, until it was abandoned due to the offender's dangerous driving.

"A short time later, the wanted vehicle has crashed as it headed south on Ruahine St," he said in a statement. "A firearm was recovered from the vehicle and a 19-year-old man was arrested at the scene."

Investigations to locate the remaining offenders are ongoing and more information will be released as it becomes available, Ward said. Armed officers and the Armed Offenders Squad are involved in the manhunt.

"We know many people in our community will be shaken by the events of this morning," Ward said.

"Anyone with information is asked to call police on 105 and reference the event number P053442225."