A group of six travellers, including several Singaporeans, was involved in an accident in New Zealand's South Island on Sunday (March 10).

The group was travelling in a silver Hyundai Imax van on the Te Anau-Mossburn Highway in the Southland region when it met with an accident with another vehicle.

The other vehicle was an orange Holden Trax sport utility vehicle (SUV), in which there were two passengers.

Photographs of the accident show the Imax van on fire.

New Zealand police told The Straits Times that the crash was reported on Sunday, at about 2.45pm local time (9.45am Singapore time).

A police spokesman, in response to ST queries on Monday, said: "There were six passengers in the Hyundai and two in the Holden, and all were taken to hospital with injuries ranging from critical to moderate. Six patients were taken to Dunedin Hospital and two to Invercargill Hospital."

Three of them were discharged from Dunedin Hospital on Monday.

In an update at 4.10pm Singapore time on Monday, the spokesman said two other victims, who were earlier said to be seriously injured, are now in critical condition.

No one has been arrested, and the police are still investigating, said the spokesman.

The Ministry of Foreign Affairs said that the Singapore High Commission in Wellington is aware of the accident and is rendering consular assistance to the Singaporeans involved.

The Southland Times reported that emergency services were still at the scene two hours after the crash.

No one was trapped in the van but a woman was trapped in the second vehicle and firefighters had to use cutting gear to get her out, a fire service spokesman told The Southland Times.

A Malaysian man, who declined to be named, was about 10 cars behind the vehicles involved in the accident.

He took his first aid kit and went to see if he could help the accident victims, he told ST on Monday.

The pharmacist, who is in his 20s and based in Queenstown, said the victims were complaining of chest pains, and one of the women had facial injuries.

He said: "Emergency services arrived in about 20 minutes, including ambulances, fire engines and helicopters. Some of the victims were air-lifted to hospital."

There were several doctors who also happened to be travelling on the highway. They, too, rushed to help the victims before the paramedics arrived, he added.

When the paramedics arrived, he also helped to translate into Mandarin, for the Singaporean victims, some of the medical terms they used.

The New Zealand Transport Agency's Twitter account for the Otago/Southland region, at 3.05pm local time on Sunday, said it had received reports of a "serious crash" blocking the highway between Block Road and Christie Road.

In an update later, the agency said power lines had fallen and the road between Centre Hill Road and Christie Road was closed.

In its latest tweet, it said the road was reopened on Monday morning, with a 30kmh speed restriction in place.

New Zealand police are appealing for information from anyone who may have seen the vehicles in the Te Anau/Mossburn area before the crash.