Four people trapped in their vehicle after a crash north of Auckland have now been freed and flown to hospital.
State Highway 1 at Dome Valley is now closed as the police serious crash unit investigates the smash, which happened north of Kraack Rd just after 11.30am today.
A St John spokesperson said two people were flown to Auckland City Hospital by the Auckland Westpac Rescue chopper and the Northland rescue helicopter; one in a critical condition, the other serious.
A third person had been taken by ambulance to Auckland City Hospital also with serious injuries.
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The fourth person was treated for moderate injuries at the scene.
Northern Fire and Emergency NZ shift manager Mark Richards said two vehicles were involved.
One of the four trapped occupants had since been freed but firefighters were still working to extract the others at 12.40pm.
Diversions are in place on SH1 at Kaipara Flats Rd to the south and at Wayby Valley Rd to the north, and will be for some time.
Police asked motorists to avoid the area and those travelling between Wellsford and Auckland were advised to take SH16 to avoid delays.