LA PAZ, Bolivia — Violent clashes over this fractured nation’s political future have claimed eight lives and unleashed a diplomatic crisis, with Bolivia and the U.S. expelling each other’s ambassadors.

Venezuela, meanwhile, kicked out its top U.S. diplomat and the South American allies demanded that Washington stay out of their affairs.

Anti-government protesters fought backers of President Evo Morales in Bolivia’s pro-autonomy east with clubs, machetes and guns Thursday, killing at least eight people and injuring 20, authorities reported.

The demonstrators also seized natural gas fields, halting half of Bolivia’s gas exports to Brazil, its No. 1 customer, for nearly seven hours, according to the affected Transierra pipeline company.

“We’re going to tolerate only so much. Patience has its limits,” Morales told supporters on Thursday. The Aymara Indian and former coca growers’ union leader has so far hesitated to mobilize the military, fearing major bloodshed.

Vice President Alvaro Garcia announced a day of national mourning.

Meanwhile, U.S. officials angered by Morales’ decision to expel Washington’s ambassador for allegedly inciting opposition protesters responded Thursday by kicking out Bolivia’s envoy to the United States.

“In response to unwarranted actions and in accordance with the Vienna Convention (on diplomatic protocol), we have officially informed the government of Bolivia of our decision to declare Ambassador Gustavo Guzman persona non grata,” State Department spokesman Sean McCormack said. Diplomats declared “persona non grata” are generally given 72 hours to depart.

Earlier on Thursday, Bolivian Foreign Minister David Choquehuanca told reporters that he had requested U.S. Ambassador Philip Goldberg’s expulsion but added that he also wrote Secretary of State Condoleezza Rice to say Bolivia “wishes to maintain bilateral relations.”

Morales had accused Goldberg of conspiring with Bolivia’s conservative opposition. Goldberg met last week with Santa Cruz Gov. Ruben Costas, one of the Bolivian president’s most virulent opponents.

In Venezuela, President Hugo Chavez, in a show of solidarity with his ally Morales, gave the U.S. ambassador to his country, Patrick Duddy, 72 hours to leave and announced the recall of Venezuela’s ambassador to Washington.

Chavez also once again accused the United States of backing a coup to overthrow him, a claim the U.S. has repeatedly denied.

“That’s enough ... from you, Yankees,” Chavez said during a televised rally, using an expletive. Waving his fists in the air, he added: “I hold the government of the United States responsible for being behind all the conspiracies against our nations!”

The conflict in Bolivia centers on Morales’ plans to redo the constitution and redirect gas revenues. Bolivia’s conservative, energy-rich eastern provinces oppose those plans, and on Thursday two weeks of protests turned violent as demonstrators stormed public offices, blocked roads and seized the gas fields.

Eight people were killed in a clash between pro- and anti-government bands outside Cobija, capital of the eastern province of Pando, said Sacha Llorenti, a deputy minister for social movements.

Presidential spokeswoman Nancy Teixera said at least 20 people were injured. Radio reports said the groups fought with clubs, machetes and shotguns. Interior Minister Alfredo Rada confirmed the use of firearms.

The protests forced the closure of various regional airports, and American Airlines canceled all flights to Bolivia. Company spokeswoman Martha Pantin said it expected flights to resume beginning Sunday.

Bolivia’s finance minister, meanwhile, said gas deliveries to Brazil would be curtailed by 10 percent for up to two weeks as workers fix a pipeline ruptured by protesters on Wednesday.

Bolivia supplies Brazil with 50 percent of its natural gas.

Brazilian state energy company Petrobras said it has adopted a contingency plan to decrease natural gas use in its units and replace gas with other fuels.

Protesters also stormed Bolivia’s Pocitos gas installation, which supplies neighboring Argentina. Plant technicians shut off gas to the country as a precautionary measure, an engineer at Pocitos told The Associated Press.

An executive with Transportadora Gas del Norte, the Argentine pipeline company that receives the Bolivian gas, said the gas flow was unaffected, however. Both officials spoke on condition of anonymity, saying they were not authorized to comment on the matter.

Opposition groups also are demanding that Morales cancel a Dec. 7 nationwide vote on a new constitution that would help him centralize power, run for a second consecutive term and transfer fallow terrain to landless peasants from Bolivia’s poor indigenous majority.

A top aide to Brazilian President Luiz Inacio Lula da Silva said high-ranking members of his government and that of Argentina are ready to go to Bolivia to try to negotiate a deal between Morales and his opponents.

Also on Thursday, Nicaraguan President Daniel Ortega announced his support for Bolivia’s decision to expel Goldberg, while Chavez threatened military intervention if Morales were to be overthrown.

“It would give us a green light to begin whatever operations are necessary to restore the people’s power,” he said.

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Associated Press writers Marco Sibaja in Brasilia, Brazil; Bradley Brooks in Rio de Janeiro, Brazil; Alan Clendenning in Sao Paulo, Brazil; Frank Bajak in Bogota, Colombia; Ian James in Caracas, Venezuela; and Matthew Lee in Washington contributed to this report.