Police are investigating how a car crashed into a concrete wall in New Plymouth early today, seriously injuring the driver

The Northgate stretch of State Highway 3 near the city centre has reopened after the crash about 1.30am.

Police had signalled the grey Holden Commodore to stop... but it took off at speed before crashing soon after.

Two people from the car are believed to have fled on foot.

Police would like to speak to anyone who may have seen the vehicle overnight in the area.