The moment an indigenous tribe made contact with the outside wold has been captured on camera.
The tribesmen, armed with bows, can be seen shouting and gesturing towards researchers across the shores of the Envira river, on Brazil's border with Peru.
In another scene, they nervously accept a bunch of bananas.
The group, believed to be members of the Rio Xinane, reportedly told interpreters that they had been attacked by "non-native people", and that many of their people had died of flu and diphtheria.
Some reports also suggested that so many natives had been "massacred" that the group had been unable to bury them, leaving vultures to eat the remains of the corpses.
Brazil's National Indigenous Foundation (Funai) filmed their team's encounter on the second day of contact with the tribe on June 30.
The tribesmen whistled and made animal sounds during the encounter, a Funai official said.
It is not clear why the group made contact, but anthropologist Terri Aquino suggested they may have come in search of "technology" such as axes, knives and pots.
It is believed to be the first direct contact since Funai began monitoring the group in 2008.
The Brazilian Amazon is believed to have the largest number of uncontacted tribes in the world.
Tribal peoples' rights group Survival International said the episode was worrying, and called on Brazil and Peru to fund better protection of the tribes' lives and lands.
“It’s vital that Brazil and Peru immediately release funds for the full protection of uncontacted Indians’ lives and lands," Survival’s director Stephen Corry said.
"Their economic growth is coming at the price of the lives of their indigenous citizens – now, their newfound wealth must be used to protect those few uncontacted tribes that have so far survived the ongoing genocide of America’s first people.”