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Troops loyal to Venezuelan President Nicolás Maduro shot tear gas and rubber bullets at U.S.-backed opposition supporters who attempted to bring foreign aid across the Colombian border on Saturday.

The conflict came as the country is torn between Maduro's socialist government and an opposing group led by Juan Guaidó, who is supported by the U.S. and many of its allies.

About a dozen trucks carrying U.S. humanitarian aid attempted to make their way across the border, according to Reuters, but Maduro's troops had partially closed the Venezuelan border with Colombia a few hours prior.

Vice President Delcy Rodriguez said on Twitter that the government was ordering the temporary closure of three crossings in Tachira state because of the "serious and illegal threats" against Venezuela's peace and sovereignty coming from Colombia's government.

In the towns of San Antonio and Urena, just across the border from Colombia, troops fired tear gas and rubber bullets at opposition activists including lawmakers walking towards the frontier and waving Venezuelan flags and chanting "freedom."

Witnesses reported constant gunfire without being able to identify the origin.

"They started shooting at close range as if we were criminals," said shopkeeper Vladimir Gomez, 27, wearing a white shirt stained with blood. "I couldn't avoid the (rubber) bullets and they hit me in the face and my back. We have to fight."

Many of the demonstrators said they were peaceful civilians who simply wanted aid because of widespread food and medicine shortages in the once-prosperous country suffering an unprecedented economic meltdown.

A man walks past boxes of USAID humanitarian aid at a warehouse at the Tienditas International Brigde on the outskirts of Cucuta, Colombia, on the border with Venezuela. Fernando Vergara / AP

"I'm a homemaker, and I'm here fighting for my family, for my children and parents, resisting the military's tear gas and soldiers on motorbikes," said Sobeida Monsalve, 42.

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Others barricaded streets with burning tires, set a bus alight and hurled stones at security forces to demand that Maduro allow aid into a country ravaged by food and medicine shortages in the wake of an economic meltdown.

National guard troops also fired tear gas in Santa Elena near the Brazilian border where people tried set up barricades to prevent armed pro-government agitators from entering.

On Friday, troops had opened fire in a village in the area killing a woman and her husband. Thirty-five National Guard troops are being held by the indigenous community in protest, the mayor of the broader Gran Sabana municipality said.

Two humanitarian aid trucks crossed the Brazilian border although they had not passed through the Venezuelan customs checkpoint, a witness told Reuters.

Venezuela’s foreign minister on Friday called the opposition's attempt to deliver aid on Saturday "a spectacle" and accused the U.S. of orchestrating the event "to generate violence" and get the military to rise up.

The U.S. State Department also said Friday that it and others have begun “pre-positioning additional humanitarian aid” for Venezuelans in Boa Vista, Brazil, near that country’s border with Venezuela.

"This life-saving humanitarian assistance is made up of 178 metric tons of locally-procured food supplies and is ready to be delivered to Venezuelans suffering from severe food shortages inside Venezuela," the State Department said.

Maduro on Thursday ordered the vast border with Brazil closed.

The violence first broke out in the village of Kumarakapay in southern Venezuela after an indigenous community stopped a military convoy heading toward the border with Brazil that they believed was attempting to block aid, according to community leaders Richard Fernandez and Ricardo Delgado.

Soldiers later entered the village and opened fire, killing the married couple and injuring several others, they said

"I stood up to them to back the humanitarian aid," Fernandez told Reuters. "And they came charging at us. They shot innocent people who were in their homes, working."

After Friday's violence that killed two, White House Press Secretary Sarah Huckabee Sanders said in a statement Friday that "The United States strongly condemns the Venezuelan military’s use of force against unarmed civilians and innocent volunteers on Venezuela’s border with Brazil."

"Venezuelan Interim President Juan Guaido has requested immediate humanitarian assistance from the international community for the people of his country, while the Maduro regime has given orders to close the borders and repress those who seek to bring aid into the country,” Sanders said.

"Egregious violation of human rights by Maduro and those who are following his orders will not go unpunished," the White House statement said.

Tensions between Venezuela and the U.S. rose after the Trump administration recognized Juan Guiadó as the country's legitimate leader.

Guiadó declared himself the country’s interim president last month and gained the support of other countries in the region and Europe.

In response, Maduro announced he was severing diplomatic relations with the U.S., expelling all American diplomats and recalling Venezuelan diplomats from the United States.

Instead, the U.S. reduced its staff at the Caracas embassy to a bare minimum but said it had no plans to close the mission. An interim arrangement allowing that was due to expire on Monday.

U.S. officials said Friday that an agreement has been reached between the two countries to extend the stay of U.S. diplomats in Caracas. U.S. officials said the agreement will allow the diplomats to remain in Venezuela for another 30 days

Trump’s national security adviser, John Bolton, canceled plans to travel to South Korea to focus on events in Venezuela, the White House said Friday.