Violence flared in Venezuela as opposition leader Juan Guaido urged the military to help oust President Nicolas Maduro as the United States upped its pressure for a change in government.
Thousands of Venezuelans came out in the capital, Caracas, early on April 30 to support what Guaido called the "final phase" of a campaign to assume power in the South American country as his supporters rallied outside an air base.
Scattered clashes occurred between security forces and backers of Guaido, with a medical center saying it was treating some 50 injured people.
Officials in Maduro's government denounced Guaido's actions as an attempted coup and said they retain the support of the military.
Defense Minister Vladimir Padrino said in a broadcast along with uniformed men that the military would continue to defend the "legitimate authorities."
"People are going to continue arriving, [military] units who are on the side of the constitution are going to be arriving," Guiado told reporters. "We invite the world to witness what is going to happen here which, as always, is within the parameters of the constitution, democratic and nonviolent as it has been up to now -- always demanding the end of the usurpation."
"Brothers -- together we are making history," he wrote on Twitter
But Maduro said in a tweet that he had "total support" from the military, but called for a mobilization of "the militias" and ended his message with "we will win."
Guaido, whose claim as interim president is backed by the United States and more than 50 other countries, appeared in a video shot next to the La Carlota air base surrounded by several heavily armed soldiers backed by a handful of armored vehicles.
He also appeared with opposition leader Leopoldo Lopez, who had previously been jailed and held under house arrest. Lopez -- who publicly reiterated Guaido's calls for the military to abandon Maduro -- later sought refuge in the Chilean Embassy in Caracas, AP reported quoting the embassy.
In Washington, U.S. national-security adviser John Bolton said three of Maduro's senior aides had pledged to help Guaido make a peaceful transition to power.
"It’s still very important for three figures in the Maduro regime who have been talking to the opposition over these last three months to make good on their commitment to achieve the peaceful transition of power from the Maduro clique," Bolton said, citing Padrino, Supreme Court chief judge Maikel Moreno, and presidential guard commander Ivan Rafael Hernandez Dala. "All agreed Maduro had to go. They need to be able to act this afternoon and this evening to be able to bring other military forces to [Guaido's side]."
U.S. President Donald Trump tweeted that Washington stands with the "People of Venezuela and their Freedom." Vice President Mike Pence said on Twitter that "America will stand with you until freedom & democracy are restored."
U.S. Secretary of State Mike Pompeo said in a tweet that the U.S. "fully supports" Guaido's call for the start of "Operacion Libertad (Operation Freedom)" and Venezuelans "in their quest for freedom and democracy."
Russia, Iran, China, and Cuba are among countries supporting Maduro, who started a second term in January following a May 2018 election marred by an opposition boycott and claims of vote-rigging, leading to mass street protests.
In March, Russia, which has substantial economic ties to Maduro's government, sent planes to Venezuela carrying nearly 100 military personnel the U.S. government believes included special forces and cybersecurity experts.
Russian President Vladimir Putin discussed the situation in Venezuela, among other topics, with members of his Security Council, Kremlin spokesman Dmitry Peskov said.
Brazil is among many of the other Latin American countries that voiced support on April 30 for Guaido -- the head of the National Assembly in the country of some 30 million -- in his push to take power.