BRASILIA (Reuters) - Two indigenous men, members of the Guajajara tribe in northeastern Brazil, were shot dead on Saturday, and two others were wounded, not far from where a prominent tribesman who defended the Amazon rainforest was also killed last month, authorities said.

Indigenous tribes in Brazil are facing escalating violence during the presidency of Jair Bolsonaro, who has promised to reduce tribal rights and encouraged the commercial exploitation of their protected lands. Tribes have faced violence especially from illegal loggers and miners.

Magno Guajajara, a spokesman for the tribe, said they did not know why the two men had been shot, whom he identified as Firmino Guajajara and Raimundo Guajajara. The men were on a highway, coming back from a meeting, when the shots were fired from a passing car, he said.

“They were shooting at everyone,” he said by telephone.

Authorities said they were investigating but did not say if anyone had been detained.

Sonia Guajajara, head of Brazil’s largest indigenous umbrella organization APIB, said the murders reflected an escalation of violence against tribes people that she said was incited by Bolsonaro.

“We are adrift, the state has ceased to protect us,” She said in a statement. “The climate of tension, insecurity and persecution against indigenous people in Brazil only increases.”

The incident happened in the Cana Brava indigenous reservation, which spans 137,000 hectares (338,530 acres)in the state of Maranhao and has 4,500 inhabitants, according to government records.

Paulo Paulino Guajajara, the “forest guardian” killed last month, was shot in a confrontation with illegal loggers on a nearby reservation.