The Southern Institute of Technology students were in a 1993 Mitsubishi station wagon, and were flown to Dunedin Hospital by helicopter, Senior Sergeant Brian Benn, of Dunedin, said.
The camper van was carrying a German family.
The driver of the Mitsubishi was trapped for more than an hour in the vehicle, which was initially in flames. Firefighters extinguished the blaze.
Snr Sgt Benn said the camper van was carrying two adults and two children.
The crash happened at 4.15pm, when the camper van turned right from State Highway 6 on to State Highway 97, heading towards Mossburn.
Three helicopters attended, two from Dunedin and one from Te Anau, as well as fire brigades from Mossburn and Lumsden.
One of the children was taken to Southland Hospital for treatment, while the other occupants of the camper van were treated at the scene.
The third passenger in the Mitsubishi was taken to Southland Hospital.
It was too early to say who was at fault, but given it was an intersection ''someone's failed to give way'', Snr Sgt Benn said.
Witnesses to the crash or to the manner of driving beforehand were urged to contact their nearest police station.
Police also attended a minor crash at Waihola, in which two cars collided outside Waihola Motors, in Greenwich St, about 7.45pm.
No-one required treatment.
Overall, however, police say holidaymakers on Central Otago roads were generally well-behaved yesterday.
About 50 calls were made through *555, to report bad driving.
Snr Sgt Benn said the number of calls through *555 was not out of the ordinary for the heavy tourist routes in the district, which includes the Crown Range Rd, the Kawarau Gorge, the Lindis Pass, Milford Sound to Te Anau and State Highway 6 from Kingston to Queenstown.
''South of the Waitaki River, people are reporting bad driving to us. That's great that the general public think it's socially unacceptable ... that helps us target people individually.
''There are five zones that we are well aware of and we do concentrate on having staff in place in those areas ... as a prevention and also because we know we're going to get reports from members of the public.''
Snr Sgt Benn said police followed up with every driver subject to a complaint through *555, even if they could not intercept them on the road.
The two biggest issues were speed and alcohol.
''The speed limit is the speed limit. It's the maximum speed in good driving conditions - it's not a target.
''It's always befuddled me why people would put their own lives in danger, and the lives of others, and when we pull them up ... they get mad at us.''
Snr Sgt Benn said Dunedin roads were quiet and driver behaviour was pretty good.
• A man has died and two others have been seriously injured in the first fatal crash of New Zealand's Christmas and New Year road toll season.
The man was driving a Nissan rental car towards Tauranga on State Highway 2 about 2.15pm on Thursday when it was in a collision with a car travelling in the opposite direction.
The two occupants of that car, aged in their 70s, were trapped in their Mazda for about 30 minutes.
The 70-year-old man was in a critical condition in Tauranga Hospital's intensive care unit while the 74-year-old woman was in a stable condition.
- Additional reporting Bay of Plenty Times
