A high-risk operation to get humanitarian aid into Venezuela descended into deadly chaos Saturday after President Nicolas Maduro's security forces fired on demonstrators and aid trucks were set ablaze.
Two people, including a 14-year-old boy, were killed in clashes with security forces that left more than 300 people wounded at various border crossings.
Despite a blockade by Maduro, opposition leader Juan Guaido had set a Saturday deadline for the delivery of food and medical aid stockpiled in Colombia and Brazil. Aid is also being held on the Caribbean island of Curacao.
Humanitarian aid, much of it from the United States, has become the centerpiece of the standoff between Maduro and Guaido, the 35-year-old leader of Venezuela's National Assembly who declared himself interim president exactly one month ago.
US Secretary of State Mike Pompeo said the United States "will take action" as he condemned violence perpetrated by Maduro's "thugs."
A boat carrying aid from the US territory of Puerto Rico had to turn back after receiving a "direct threat of fire" from Venezuela's military, Governor Ricardo Rossello said, calling the move a "serious violation against a humanitarian mission" that is "unacceptable and outrageous."
"I will never bow down, I will never give in. I will always defend our country with my own life if necessary," Maduro told a rally of his supporters in the capital Caracas, after thousands had marched through the city under the slogan "Hands off Venezuela."