As the latest clashes broke out in the capital with riot police firing tear gas to push back stone-throwing demonstrators, an unidentified man on a motorcycle shot the boy in the head yesterday, witnesses said.
Thousands of protesters clashed with riot police deployed to contain what the opposition vowed would be the "mother of all protests."
The opposition has accused Maduro of letting state forces and gangs of armed thugs violently repress demonstrators as he resists opposition pressure for him to quit.
A 23-year-old woman, Paola Ramirez, died after being shot in the head in the western city of San Cristobal, the state prosecution service said later in a statement.
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Non-government rights group Provea said the woman died "in the context of the demonstrations."
Prosecutors said they were investigating both killings.
Authorities had already reported five other people killed, including a boy of 13, in protests around the country earlier this month.
Pressure on the leftist leader has been mounting since 2014, as falling prices for Venezuela's crucial oil exports have aggravated an economic crisis, creating severe shortages of food and medicine in the state-led economy.
The crisis escalated on March 30, when the Supreme Court tried to take over the powers of the National Assembly, the only lever of government Maduro and his allies do not control.
The court partly backtracked after an international outcry, but the tension only increased when authorities slapped a political ban on opposition leader Henrique Capriles on April 7.
"We have to end this dictatorship. We're fed up. We want elections to get Maduro out, because he's destroyed this country," said protester Ingrid Chacon, a 54-year-old secretary.
The president in turn has urged his supporters, the military and civilian militias to defend the socialist "Bolivarian revolution" launched by his predecessor Hugo Chavez in 1999.
"The hour of combat has arrived," Maduro said this week after ordering the military to mobilise in the face of the protests.