One person was taken to North Shore Hospital after a car rolled on the Northern Motorway this afternoon.
Emergency services were called to the crash just north of the Onewa Road off-ramp at 1.09 am.
A spokesman for St John said that one person was serious and transported to the North Shore hospital.
"Two others were in a less good condition."
The police said that a vehicle blocked lanes and that all northern lanes are currently closed, and that traffic to the north is diverted from the highway at Onewa Rd.
"This will cause a significant traffic disruption and the police will encourage motorists to avoid the area if possible," said a spokesman for the police.
All northern traffic is driven off the highway at Onewa Road and traffic is rebuilt over the Auckland Harbor Bridge.
The police are trying to reopen some of the lanes as soon as possible.
Drivers are advised not to drive to the Auckland Harbor Bridge and to use alternative routes to the north via the Western Ring Route on SH16 and SH18.
Expect delays and avoid the area if possible.
There is a tail queue at Newmarket and queues near the accident associated with rubber checkers, according to Newstalk ZB's Time Saver Traffic.
The Serious Crash Unit is present at the incident.
More to come.