The United States has stockpiled aid on Colombia's border with Venezuela at the request of opposition leader Juan Guaido, whom Washington and other dozens of other Western governments have recognized as Venezuela's legitimate president since Maduro held elections previous year decried as fraudulent. Guaido has accused Maduro of rigging his re-election and is demanding a new vote.
As tensions rose on both sides of the border, Maduro severed diplomatic relations with Colombia over its backing for his rival, who had crossed into the neighboring country for the handover of the aid.
The violence came just hours before dueling concerts were expected to begin on the country's western border with Colombia, where tons of donated food and medicine are stored.
Friday's killing came as a fundraising concert for Venezuela - backed by British billionaire Richard Branson and featuring major Latin pop stars like Luis Fonsi and Maluma - kicked off in the Colombian frontier town of Cucuta, where the United States has been stockpiling humanitarian aid to ship across the border this weekend.
British billionaire Richard Branson is sponsoring a Live Aid-style concert featuring dozens of musicians including Latin American rock star Juanes on one side of the border crossing that Colombian officials have renamed the "Unity Bridge", while Maduro's socialist government is promising a three-day festival called Hands Off Venezuela on the other.
At least two people have died and 17 were injured Friday in a standoff between a local indigenous community and the Venezuelan military over deliveries of humanitarian aid, according to local authorities.
The clash occurred in southeastern Bolivar state near to the border with Brazil, which Maduro ordered closed on Thursday.
U.S. Vice President Mike Pence, in a message on Twitter on Saturday, said: "To Juan Guaido and all the people of Venezuela taking a stand for freedom and humanitarian relief: Estamos con ustedes. The world is watching". The vehicles are driven by Venezuelans and escorted by Brazilian police, organizers said.
Also in Colombia the concert has drawn criticism, mainly because of ongoing extreme poverty in neglected regions like Choco and La Guajira, which lies on the border with Venezuela, and the politicization of Venezuela Aid Live. Meanwhile aid is being stockpiled in Colombia, Brazil and the Caribbean island of Curacao because of Maduro's ban.
The 35-year-old lawmaker was greeted there by the presidents of Colombia, Chile and Paraguay, three of the nations that have recognised him as interim president.
Guaido has set a Saturday deadline for the entry of humanitarian aid, saying as many as 300,000 Venezuelans are in dire need of food and medicines after years of shortages and malnutrition. The leaders greeted the crowd before the concert ended.
"We trust in God to open the way. and to destroy the enemy", he said, before leading a recitation of the Hail Mary and the Lord's Prayer.
"The truth is that not even 10 concerts will make damned Maduro leave office", said Darwin Rendon, one of the 3.4 million Venezuelans to have emigrated since 2015 to find work.
This weekend's confrontations cap a month-long run of protests and sanctions aimed at unseating Maduro, 56, the hand-picked heir of the late President Hugo Chavez.
The claim is significant because President Nicolas Maduro has been able to retain power largely because of his military support.
Moscow has blasted Washington for using aid as a "convenient pretext for conducting military action".