Several investigations are underway after an incident in Auckland's Manurewa which has left one person dead, and another critically ill

Police say they watched the incident play out.

One of their cars spotted a Mitsubishi pulling out of Sharland Road about 1am, closely followed by an Isuzu.

Officers signalled for the Isuzu to stop on Roscommon Road, after concern it was chasing the other vehicle.

The Isuzu hit the Mitsubishi, causing it to spin off the road and hit a tree.

The passenger died at the scene and its driver was left in a critical condition.

The Isuzu's driver was arrested at the scene with minor injuries.