It was the latest in a week of clashes over a mounting crisis driven by food shortages.
Some 71 people were arrested on Tuesday alone, according to rights group Penal Forum.
Two young men had already been killed in protests during the last week, according to authorities. He was shot at a protest in the central city of Barquisimeto on Tuesday.
No major protests were announced for yesterday, but opposition leaders called for huge rallies on April 19.
A 36-year-old man was killed the same night in Barquisimeto, prosecutors said.
Protesters say they have also been encouraged by stronger condemnation from American and European nations in the last two weeks.
"We would defeat them in a matter of hours and radicalize this Bolivarian Revolution", he continued, speaking during his weekly television program "Sundays with Maduro". "We will stay in the street!" he wrote on Twitter.
State officials via social media have shown images and videos of demonstrators vandalizing public property and throwing rocks at police.
"I want to see Venezuela free of dictatorship".
Venezuela's Ministry of Defense called on Almagro and the OAS Tuesday to condemn acts of violence, such as reports from Venezuela's Ombudsman that seven of its offices had been attacked in the anti-government protests.
Opposition lawmaker Alfonso Marquina said on Thursday a fifth protester had died.
Drew Pomeranz dominant in debut, Boston dismantles Baltimore
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Police also reportedly broke up a protest in the state of Vargas which borders Caracas.
"Why was there no violence? We are the guarantors of peace in this country", said opposition congress deputy-speaker Freddy Guevara in a speech.
An employee of a grocery and liquor store cleans up the place after looters entered store during a protest last night in Caracas, Venezuela, Wednesday, April 12, 2017.
That will be the next big showdown in an increasingly tense crisis that has raised worldwide concerns for stability in Venezuela.
Maduro's adversaries are demanding the government call delayed state elections, which polls suggest would not go well for the ruling Socialists. Dozens have been arrested, and leading opposition figure Henrique Capriles has been barred from holding office for 15 years.
Those moves have raised worldwide condemnation including from the United States and the European Union.
The opposition had planned protests in more than 300 municipalities for Thursday, with the aim of diluting the power of government security forces.
It said the summit here would be to conclude discussions on health insurance; strategic options for diplomatic representation; greater participation of non- independent member states; agriculture and support services (regional transport); the blue economy; and climate change and sustainable land management.
Maduro supporters staged their own rally on Tuesday to mark the anniversary of a short-lived coup against Maduro's predecessor and mentor, the late leftist firebrand Hugo Chavez, in 2002.
He says the economic crisis and efforts to get rid of him are a capitalist conspiracy.