"A tour company vehicle was in a crash and flipped over at the salt flat itself, and as a result, five people were killed and another three injured," said Uyuni police chief Rodolfo Salazar.
Four of the deceased were women, he said, but no identities were immediately given.
The injured were taken to a hospital in Potosi, 200 kilometres (125 miles) away.
Early indications were the vehicle was speeding, Salazar said.
Salar de Uyuni is the world's largest salt flats area, and Bolivia's top tourist attraction.