About 1am in Roscommon Rd in Manurewa, officers spotted a Mitsubishi vehicle being chased by an Isuzu and signalled for the Isuzu to stop after becoming concerned.
The Mitsubishi had pulled out of Sharland Rd closely followed by the Isuzu.
Moments after lights and sirens were activated, the Isuzu hit the Mitsubishi, causing the vehicle to leave the road and hit with a tree.
Officers immediately rendered first aid but the passenger of the vehicle died at the scene. The driver was taken to hospital in a critical condition.
The driver of the Isuzu was arrested and taken to hospital with minor injuries.
Police have launched a critical incident investigation.
Counties Manukau District Commander Superintendent Shanan Gray said a scene examination had been completed by the Serious Crash Unit and the road had reopened.
There were several investigations under way, Gray said.
This included notifying the Independent Police Conduct Authority.
