Venezuela opposition votes against Maduro, woman shot dead

(Adds details of fatality, opposition leader, vote estimate)

By Alexandra Ulmer and Andreina Aponte

CARACAS, July 16 (Reuters) - Gunmen in Venezuela shot into a crowd of voters on Sunday, activists said, killing one woman and wounding three others during an unofficial referendum organized by the opposition to push for an end to two decades of socialist rule.

The opposition Democratic Unity coalition said a pro-government "paramilitary" gang opened fire in Caracas' poor neighborhood of Catia, where thousands were participating in the opposition event. Video footage showed people scattering as gunshots rang out, many taking sanctuary inside a church.

"The day was stained by the killing of a Venezuelan woman who protesting and exercising her rights," said opposition leader Freddy Guevara of the killing of Xiomara Escot. "But violence cannot hide what has happened. The people are not afraid and are clear in their decision."

Sunday's symbolic poll, which asked voters' opinion on President Nicolas Maduro's plan for a controversial new congress, was aimed at denting his legitimacy further amid a crippling economic crisis and months of anti-government protests in which some 100 people have been killed.

Maduro, 54, has denounced the plebiscite as illegal and meaningless. Instead, the former bus driver and union leader is campaigning for an official July 30 vote in support of the proposed new assembly, which would have the power to rewrite the constitution and dissolve state institutions.

The opposition cast Sunday's unofficial referendum as an act of civil disobedience that will be followed by "zero hour," a possible reference to a national strike or other escalated actions against the president.

Lines formed early at makeshift polling stations at theaters, sports fields, and traffic circles in the oil-rich nation of 30 million as Venezuelans furious over food shortages and rampant inflation sought to make their voices heard.

There was a festive atmosphere under the Caribbean sun in most places, with people blasting music, honking car horns, waving Venezuelan flags, and chanting "Yes we can!"

More than five million people had cast ballots at 2,000 centers, the opposition said, as voting was extended into early evening so everyone still waiting in line could have their say.

"Maduro has done everything very badly, and now, via a fraudulent constituent assembly, he wants to gain time, but his time is up," said shopkeeper Rafael Betancourt, voting in late leftist leader Hugo Chavez' home state of Barinas, which has flipped to the opposition.