A further five people were hurt in the two-vehicle collision, police said.
Two people had serious injuries and three others had minor to moderate injuries.
Emergency services were called to the incident in Braemar Rd, between the intersection with Tekapo-Twizel Rd (State Highway 8) and Hayman Rd, at Tekapo in the Mackenzie District, at 10.55am.
Three rescue helicopters were sent to the scene.
A Chinese Embassy spokeswoman told Stuff that police told her the three dead were part of a group of five Chinese tourists in a car that collided with a four-wheel drive.
The two others in the group were currently in Dunedin Hospital, she said.
One of the first people at the scene of a triple fatal crash near Tekapo says he arrived to a "mangled mess" on the unsealed scenic road that is popular with tourists.
Braemar Station Shearers Lodge owner Hamish Mackenzie said he arrived at the scene shortly after the crash.
"It was pretty horrendous. There were a lot of emergency crew there, and a people carrier sideways on the road, which looked to have had a head-on crash with a double-cab truck.
"The people carrier was untidy, a mangled mess. Emergency crews were using the jaws of life to cut it open. Some guys I was talking to at the scene said there were tourists involved."
The truck appeared to belong to be carrying forestry workers, he said.
The crash happened about halfway along the unsealed Braemar Rd, between Lake Pukaki and Tekapo. It was a "quite a dangerous" section on the country road.
"There are a lot of blind hills," Mackenzie said.
"There have been crashes along Braemar Rd before, but not that spot. I have never seen anything that horrendous."
Rain overnight would have dampened the dust down, making for relatively good driving conditions, Mackenzie said.
The scenic road was becoming increasingly popular with tourists.
"There are views of the Southern Alps, it is pretty scenic and so more tourists are coming along the road, but it is also a country road so needs to be treated with respect.
"This kind of thing shakes the hell out of the community. I've already had a number of phone calls checking it wasn't us. I know a lot of the emergency crews too, they are all volunteers. It is all pretty humbling."
Mayor 'devastated'
Mackenzie District Mayor Graham Smith said he was devastated by the news.
"My biggest sympathy goes out to all those concerned and those families that have been caught up in this," he said.
"I send my grateful thanks to the emergency teams that attended. They have had to deal with a very tragic accident."
Smith said Braemar Rd was a shingle road.
"It is a back road that runs from State Highway 8 through to the edge of Pukaki. It is not that busy, but it is one of those roads that you have to stay a car and a half behind and mind where you drive.
"It is reasonably narrow in places, so you have to be conscious and look ahead, and careful to stay hard left on corners.
"I don't know what has gone wrong, but it is extremely tragic. I know my community and I know they will be devastated by what has happened."
Braemar Station Shearers Lodge owner Julia Mackenzie news about the crash just down the road was "awful".
She said it was not a particularly dangerous road, but was being increasingly used because of its spectacular views of Mt Cook and the Mackenzie Basin.
"It is not a particularly dangerous road - it's a road we use all of the time - but the section where they crashed there are a lot of rises, up and down.
"It is one you really need to stick left on."
Police have asked motorists to avoid the area.
