The rest suffered moderate to minor injuries in the form of cuts, bumps, bruises etc and were taken to Taupo Hospital, some by helicopter after emergency services ran out of ambulances.
The main injuries were to a vanload of about a rugby players from Ohakea Air Force base who were heading south after playing in Auckland.
Earlier, Taupo resident Debbie Ward spoke hearing a massive bang and the screeching of tyres.
"Our property is on the hill so we overlook that stretch of road up above the crash, so we could see there had been disaster."
Ward, who has lived on the property for 12 years, ran out to look over the fence with her husband, where they saw "a big pile-up" of vehicles.
Other witnesses later described the vehicles involved in the crash as including a truck, motorcycle, ute and minivan.
"I went inside and called 111 and they said 'do you want the police, ambulance or fire?' I said, 'I think we're going to need all of them'."
The 56-year-old said a number of people emerged from a van, which was "pulled to bits".
There was a large response from the emergency services, with some people trapped in the vehicles.
When the ambulances arrived, victims could be seen sitting on the side of the road with blankets, "in shock obviously".
Ward said roadworks were taking place this morning, and it looked like the vehicles were waiting at a stop sign when a truck came up from behind, didn't see them and ploughed into them.
A motorbike was "just a mess" on the side of the road.
Ward had seen a handful of incidents on the stretch of road, but this was "certainly the messiest".
She was feeling shaky after the crash, and felt for the victims.
"There was a lot of innocent people hurt today, but there didn't seem to be anybody killed so that's a blessing."
The police Serious Crash Unit is investigating.
