Thousands are protesting in Venezuela's capital in a bid to topple President Nicolás Maduro's government.
Four people reportedly died in overnight clashes ahead of the opposition protests.
Mr Maduro was sworn in for a second term in early January, after a poll considered a sham by much of the international community.
Venezuela has been in economic freefall for a number of years under his leadership.
Hyperinflation and key shortages, including of food, has forced millions out of the country.
US President Donald Trump has said he recognises Venezuelan opposition leader Juan Guaidó as interim president.