The man was treated by St John paramedics near a BP station in Great North Rd, Te Atatu South, this morning before being transported to Auckland Hospital.
Police also locked down Hutchison Ave in the suburb of New Lynn.
Police believe the man drove to the petrol station after being shot at a house in the street, an officer said.
He said police were working to determine exactly what happened, however, neighbours initially reported the incident after hearing gunfire.
People at the property were helping with the inquiry. Police would not say if they had found the gun used.
Second serious incident
This afternoon, officers were called to another serious incident in West Auckland.
Police were outside a house in Laura St, Kelston, telling those inside to come out and “no one will get shot” as the police Eagle helicopter circled overhead.
Police would only confirm they are “attending an incident in Kelston” with updates to follow “in due course”.
About three people were seen in handcuffs on the street, flanked by armed officers.
Armed police at mall carpark
Police thanked New Lynn residents for their understanding after a morning of disruption.
Earlier, multiple cars were seen rushing to the New Lynn area, while the police Eagle helicopter circled overhead.
“We believe he was shot at the house but we’re working to determine the exact circumstances and who was involved," an officer said.
Hutchinson Ave was now out of lockdown, but up to six police cars as well as armed police remained outside the brick home which was still taped off this afternoon.
RNZ earlier reported that armed police swarmed a carpark at the New Lynn Mall. Startled shoppers said two police cars approached a parked vehicle before officers slowly advanced towards it with weapons drawn.
A Hutchinson Ave resident said armed police shut down the area just before 10am as he returned from a walk with his daughter.
“We were just doing our normal Saturday routine and all of a sudden there’s two police officers came down the (neighbouring) driveway with rifles asking us to hide."
Later, he heard police using a microphone to address a person in a nearby home down the road.
“They were on the loud speaker saying, ‘We have armed police, please come out with your arms up'”.
Police said they were called about 9.40am and were working to establish the circumstances leading to the incident.
"One person has been taken to hospital with serious injuries,” a spokeswoman confirmed.