Thousands of indigenous Indians have invaded several farms close to Brazil's border with Paraguay in an attempt to reclaim ancestral land.
Indians in the region have long been at odds with ranchers
Brazilian police said the members of the Guarani and Kaiowa peoples appeared with painted faces and bearing traditional weapons.
Occupants of the ranches in the state of Mato Grosso do Sul fled in fear.
Two farms have so far been seized since the invasions began last week, according to the Brazilian media.
Reports from the area said Indians armed with bows and arrows and shouting in their native language took over the farms located near the city of Iguatemi.
Two thousand Indians had also set up camps at the main entrances to other farms in the region, the Estado web site reported.
The Indians were said to be performing war rituals ahead of more planned invasions.
Brazil's National Indian Foundation (Funai) says all the ranches are in an area covering traditional lands belonging to the two closely related tribes.
The Indians have long been at odds with farmers who have moved into the area and now use the land for large-scale cattle-ranching.
The Guarani have one of the highest suicide rates in the world, according to the pressure group Survival International.
More than 300 out of a population in Brazil of 30,000 have killed themselves since the mid-1980s.