The accident happened yesterday on a highway linking Paraty, in Rio de Janeiro state, with the coastal area of Trinidade, a fire department spokesman said. Rescue workers and crash investigators were at the scene.
Local media reported the crash took place on a winding road on a descent known in Portuguese as "God Help Me Hill."
Brazilians were enjoying a long holiday weekend for Independence Day today. That meant more people were on the roads to take advantage of a three-day getaway to the beach.
It sits on the border of Brazil's two most populous states, Rio and Sao Paulo. It also is popular with foreign visitors.
About 43,000 people die each year on Brazil's roads. Before the country's economic boom cooled, accidents surged by 24 per cent between 2002-2012 and about 10,000 new cars took to the roads each day.
In March, 54 people were killed when a bus taking them to a religious event plunged off a cliff in the southern state of Santa Catarina.