A member of the public was hit by the vehicle as the suspect drove off, police said in a statement on Twitter.
"Cordons are in place and schools in the immediate area have been advised to lock down," Superintendent Naila Hassan, Waitemata district commander, said in a statement.
Gun crime remains relatively rare in New Zealand, where laws have been tightened twice since a gunman killed 51 Muslim worshippers in Christchurch last year in the country's worst peace-time mass shooting.
The country's lawmakers on Thursday passed legislation to create a new firearms registry that licence holders will be required to update as they buy or sell guns.