Twelve people remain in hospital after a car and tourist bus collided in the Otira Gorge near Arthurs Pass yesterday.
Seven patients are in Christchurch Hospital - two in a critical condition and five serious - and five are in Greymouth Hospital with minor to moderate injuries.
The Herald understands police from around New Zealand have been called upon to assist with translating victim and witness statements. The bus passengers were all Asian tourists.
In total, 36 people were caught up in the crash and the bus was left lying on its side after the collision.
The crash happened on State Highway 73, about 1km from the rock shelter at Windy Point in the South Island high country.
At least one person was trapped under the bus.
The New Zealand Transport Agency said State Highway 73 would reopen at 6pm but motorists should expect delays until around 7.
The bus was travelling from Franz Josef to Christchurch. Three people were in the van, a police spokesperson said this afternoon.
The Canterbury West Coast Air Rescue Trust said four helicopters were deployed to deal with the "mass casualty situation".
Simon Duncan of Canterbury West Coast Air Rescue Trust said one helicopter was sent from Nelson, another from Greymouth, and two from Christchurch.
The accident happened on the western side of Otira, he said.
The Greymouth Star
understood a passing motorist was flagged down at the crash scene about 11am to seek help.
Then someone travelled to nearby Arthur's Pass village, where the accident was reported to emergency services.
Four ambulances were sent to the scene, as were volunteer firefighters from Greymouth and Kumara.
St John spokesman Ian Henderson said the ambulance service was alerted at 11.05am.
The Greymouth-based NZCC West Coast Rescue Helicopter was sent by 11.20am.
Mr Henderson said St John sent "mass casualty incident equipment and medical resources" to the scene.
Three people were flown to Christchurch Hospital emergency department, arriving by 1.26pm.
Meanwhile, St John paramedics assessed more than 20 people at the scene for injuries.
Eight patients had arrived at Christchurch Hospital by 2.20pm with injuries ranging from "minor to very serious", St John said.
Of the seriously injured patients, one was a woman in her 50s, the other in her 20s.
Another eight crash victims were taken by ambulance to Grey Base Hospital in Greymouth.
Mr Henderson said the patients taken to Grey Base all had minor or moderate injuries.
The remaining bus passengers escaped injury. Police were taking these passengers back to Greymouth, St John said.
Police said all 36 people involved in the crash were tourists.
Tasman road policing manager Inspector Iain McKenzie said the van was a rental vehicle.
The state highway was closed after the smash.
A diversion for traffic heading from the West Coast towards Canterbury was in place at the small settlement of Jacksons, northwest of Otira.
The crash and road closure meant Jacksons Historic Tavern was largely cut off this afternoon, with the road closed on both sides outside the building.
Staff at the tavern understood the bus in the crash was a tour bus.
A tavern manager said she hoped the road would reopen soon.
She said the road closure meant the tavern had no customers on what would otherwise have been a very busy day.
"Due to the seriousness of the crash, the highway is unlikely to reopen before 6pm," a New Zealand Transport Agency spokesman said.
Police said the road was likely to be blocked until this evening. A police serious crash investigator was on the way to the scene.
Motorists were urged to avoid the area as there will be significant delays.
Tasman police spokeswoman Barbara Dunn said motorists intending to travel along SH73 today were "urged to stay away" and make alternative plans.
The New Zealand Transport Agency said motorists planning to travel to and from the West Coast via Arthur's Pass should drive through Lewis Pass instead.
Road safety campaigner Clive Matthew-Wilson claimed the crash was the latest in "a series of accidents" involving tourist drivers.
"While the national figure is quite low, in certain locations, such as Westland, the percentage of accidents involving foreign drivers is around 37 per cent - an alarming figure given the relatively small amount of traffic using those roads."
- NZME, Newstalk ZB and Greymouth Star. Additional reporting by Amelia Wade