An eye witness to a multi-vehicle crash on Auckland's State Highway 1 claims three people have died at the scene.
Police earlier said there were "multiple people" with critical injuries in the crash near Ramarama that was reported at 1.47pm on Monday and which has closed the highway in both directions.
No further information has been released by police.
Asked at today's post-Cabinet media briefing about the accident, Tranport Minister Simeon Brown said "Obviously it's a very tragic incident, there's been a number of fatalities but obviously there's an investigation and closure in place."
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Tamati Cassin, a motorist who arrived at the scene about 30 seconds after the crash, said he saw three bodies in a van as well as three other people with injuries.
As he approached the scene in his car, Cassin said he saw a "big dust cloud" across the motorway and the wire from a metal barrier was strewn across the lanes.
"I had to pull over and I got out of my car - I wish I didn't now, I wish I didn't see the bodies.
"There were several cars involved but the van was the worst and even the truck was pretty smashed up on the cab it's a tragic, tragic accident."
Cassin said everyone got out of their cars to try and help the injured and dead but it was "chaos" and no one was sure what to do.
"I just really feel for the driver of the truck and the people who have passed, I get to go home to my partner and kid but they won't get to."
He said over an hour later, he was still in traffic trying to get home to Papakura.
Photo: SUPPLIED
St John said it sent 10 vehicles to the scene, including a helicopter, at 1.45pm and treated eight patients in varying conditions.
Six patients were transferred to "various destinations" including Auckland City Hospital and Middlemore Hospital.
Of the eight patients treated, St John said one was critical, three were moderate and four had minor injuries.
NZTA said all lanes on SH1 between Bombay and Ramarama are closed due to the significant crash.
Speaking to Checkpoint, NZTA Auckland systems manager Paul Geck said the worst case scenario would be the road remaining closed until 5am on Tuesday.
Photo: SUPPLIED
At this stage, Geck said the closure will "go into tonight" but he could not give an exact time.
Geck said there were "reasonable queues" on the motorway and traffic was slow on the detour route through Great South Road.
He said parents should still be able to get to local schools but there would be "significant delays".
Geck said people should check NZTA's social media updates and travel times before they travelled - and plan to delay travelling both north and south in the area if possible.
A livestream video from the scene of the crash showed a van and a car which appeared to be badly damaged, along with a truck which was off the side of the motorway.
A crowd of people could be seen helping those involved in the crash, and giving first aid to a person lying on the ground.
There was debris strewn across all four lanes.
Those travelling south will be diverted at Ararimu Road, Ramarama and northbound motorists will be diverted at Mill Road, Bombay.
People should expect delays.
The Serious Crash Unit has been advised.