Polling stations closed late Sunday in an autonomy vote in Bolivia's richest province declared illegal by the national government, but fears remained that violence that marred balloting would continue, local television reported.
At least 20 people were hurt in clashes in the eastern province of Santa Cruz between autonomy supporters and opponents, the chief-of-staff in Bolivia's government, Alfredo Rada, told reporters in La Paz.
A few polling stations in the province continued to operate past the 4:00 pm (2000 GMT) closing time because they opened late, the television said.
Initial exit-poll results were expected after 6:00 pm.
The regional referendum aimed at giving Santa Cruz control over its land and finances -- including massive gas reserves vital to Bolivia's economy -- as well as the right to create its own security force.
But socialist President Evo Morales has called the vote unconstitutional and vowed to ignore its result. His military chiefs said they viewed the poll as a threat to national territorial integrity.
Following several clashes between pro-autonomy militants and indigenous groups backing Morales, there were concerns that unrest may widen.
Three other neighboring opposition-run provinces are to hold their own autonomy votes next month, and two more are thinking of also following suit.
The defiance against Morales was triggered by his efforts to rewrite the constitution to give more of the nation's wealth to the indigenous majority -- of which he is part -- and to limit the size of large landholdings.
Most of the inhabitants of the lowlying, wealthier east of Bolivia are of European descent and often show disdain for the country's ethnic Aymara and Quechua indigenous majority.