A high-speed street race in Palmerston North ended in two separate crashes last night, leaving one man dead and another seriously injured.

A police patrol spotted two dark-coloured Honda Civics racing down Pioneer Highway in excess of 100km/h at about 11.20pm, Detective Senior Sergeant Craig Sheridan said.

The patrol gave pursuit and activated its warning lights as the cars headed south towards State Highway 56.

Both cars turned off their lights, and the patrol switched off its warning lights as it attempted to follow the vehicles.

One of the cars was found crashed at the intersection of Rongotea Road and No 1 Line with its two occupants uninjured.

Police established the car had earlier been stolen from Lombard St, in Palmerston North.

After speaking to the occupants, police were sent to check Pioneer Highway near the city boundary, Mr Sheridan said.

The second Honda was found crashed about 100m south of Maxwells Line.

The passenger, a 25-year-old Palmerston North man, was found dead, while the driver was taken to Palmerston North Hospital with serious injuries.

The serious crash unit is investigating both accidents.

The crash sites have been examined, and police were interviewing survivors and witnesses.

Anyone who may have seen the two Honda Civics on Pioneer Highway, SH56 or Rongotea Rd is asked to contact police.

Police said they would also like to speak to the occupants of an unrelated vehicle that turned right out of Maxwells Line onto Pioneer Highway before the first crash.

The 16-year-old driver of the stolen car has been arrested and charged with unlawfully taking a motor vehicle, while his 16-year-old passenger has been charged with unlawfully getting into a motor vehicle.

Both will appear in Palmerston North Youth Court at a later date.

Police will decide whether further charges are necessary once the investigation is complete.