Early exit polls indicate more than 80 percent of voters in a referendum in Bolivia's eastern state of Santa Cruz cast ballots in favor of autonomy.
Santa Cruz residents have already begun to celebrate Sunday's vote. It is not clear when the final results will be in.
Supporters of the autonomy referendum are seeking greater control over the region's government and natural resources. They also want to protect large plantations and ranches from Bolivian President Evo Morales' land redistribution proposals.
The president has called the autonomy initiative illegal and unconstitutional. However, in a speech Sunday he said he is willing to discuss autonomy with state governors seeking looser ties to La Paz.
Opponents of the measure clashed with voters at several polling stations on Sunday. Authorities say dozens of people were injured.
Critics of the autonomy measure accused business leaders in the east of trying to stop tax money from going to poor communities in the west. Supporters said some of that money should benefit needy residents in the east.
Three other areas in eastern Bolivia have scheduled autonomy votes in coming weeks, and two others also are considering votes.
Some information for this report was provided by AFP and AP.