A 61-year-old woman was killed and four people wounded in shooting that erupted after government supporters on motorcycles swarmed an opposition polling site in a church in the traditionally pro-government Catia neighbourhood of western Caracas.
The opposition mayor of the Caracas borough of Sucre, Carlos Ocariz, said pro-government paramilitary groups attacked voters outside the Our Lady of Carmen Church around 15:00.
The chief prosecutor's office said Xiomara Soledad Scott, a nurse, had been killed and four others wounded in the incident.
Video posted to social media showed massive crowds outside the church, then hundreds of people running in panic outside the church as motorcycle-riding men zoomed past and shots rang out.
Gunshots were fired while venezuelans were voting.
Translation by Some Little Llama:VenezuelaVotaEn14Dias Venezuela pic.twitter.com/VD9dgnLY9O
- TylerPreston20 ???? (@TylerPreston20) July 16, 2017
Maduro made no mention of the incident in comments on state television shortly after the official close of opposition polls at 16:00, but he called for an end to violence that he blamed on the opposition.
"I'm calling on the opposition to return to peace, to respect for the constitution, to sit and talk," Maduro said. "Let's start a new round of talks, of dialogue for peace."
In what appeared to be smaller numbers in many parts of the capital, government supporters went to polling stations in a rehearsal for a July 30 vote to elect members of the assembly that will retool Venezuela's 1999 constitution.
The opposition says that vote has been structured to pack the constitutional assembly with government supporters and allow Maduro to eliminate the few remaining checks on his power, creating a Cuba-style system dominated by his socialist party.
The success of the opposition's symbolic referendum will be measured by how many millions participate. Democratic Unity, a coalition of some 20 opposition parties, has printed 14 million ballots for voters inside and outside the country of 31 million people.
Few expect turnout that high but analysts say participation by more than 8 million people would significantly hike pressure on the government.
Participation appeared to be high, with large crowds of people lining up at tables in churches and parks across the capital.
"Since we opened at 7 a.m. the line hasn't let up," said Pedro Garcia, organiser of a voting station filled with hundreds of people in the south Caracas neighbourhood of El Valle, a stronghold of government support that has been weakening in recent years.
'No food, no medicine, no security'
Juan Madriz, a 45-year-old insurance company employee, said he didn't object to rewriting the constitution per se, but rejected Maduro's decision to do so without putting that decision to a vote, as his predecessor Hugo Chavez did.
"If they're forcing us, it isn't democracy," Madriz said.
Isabel Santander, a 67-year-old retired auditor, said she was voting against the constitutional assembly as a protest against the country's economic collapse.
"I signed because there's no food, no medicine, no security," she said. "There's no separation of powers, no freedom of expression."
Maduro and the military dominate most state institutions but the opposition controls the congress and holds three of 23 governorships. The country's chief prosecutor has recently broken with the ruling party.
The opposition is boycotting the constitutional assembly. Instead, it called backers to 2 000 sites across the country to fill out ballots featuring three yes-or-no questions.
Do they reject the constitutional assembly? Do they want the armed forces to back congress? Do they support the formation of a government comprised both of Maduro backers and opponents?
The government calls the opposition vote a manipulation aimed at destabilising the country, and has been urging its supporters to participate in the constitutional assembly, which it calls a way of restoring peace to Venezuela.
"Some comrades and brothers may be worn out by the right's great media campaign. Now they've invented this July 16 thing to put the burden on their own people and evade their responsibility," socialist party Vice President Diosdado Cabello said on Saturday. "That's how the right is, manipulative, fooling their own people."
Polls show that barely 20% of Venezuelans favour rewriting the late Hugo Chavez's 1999 constitution - about the same level of support as for Maduro.
For the government-backed rehearsal, hundreds lined up outside a school in El Valle guarded by heavily armed soldiers and militiamen, waiting quietly to place a practice vote that also served as a show of support for the government.
"Our president Chavez supported the poor, the people," said Yveth Melendez, a 41-year-old homemaker. "Today we're following his legacy, with President Nicolas Maduro ... The constitutional assembly is something that benefits the people."
Opponents of Venezuela's government blame it for turning one of the region's most prosperous countries into an economic basket case with a shrinking economy, soaring inflation and widespread shortages. The government blames the crisis on an economic war waged by its opponents and outside backers. The petroleum-rich nation has been hit hard by falling world oil prices.
Clashes between protesters and police have left at least 93 people dead, 1 500 wounded and more than 500 behind bars.