( CNN ) -- Denouncing election irregularities , Venezuelan opposition candidate Henrique Capriles Radonski demanded a recount and said early Monday that he will not recognize the country 's presidential results `` until every vote is counted . '' His comments came less than an hour after officials said the man former Venezuelan President Hugo Chavez handpicked to be his successor had won the country 's presidential vote . With 99 % of votes counted , Nicolas Maduro won 50.66 % of votes , National Electoral Council President Tibisay Lucena said , calling the results `` irreversible . '' Capriles won 49.07 % of votes , she said . Fireworks erupted over Caracas as Maduro spoke to cheering supporters , calling on Venezuelans to respect the results and respond peacefully . `` I have won by nearly 300,000 votes . It is the decision of the people , '' he said . The closely watched election was the second time in just over six months that voters in the South American country cast ballots in a presidential election . Chavez , who ruled Venezuela for 14 years , celebrated a triumphant re-election victory in October . After his death on March 5 , authorities announced new elections to select his successor . Maduro , 50 , was the United Socialist Party of Venezuela 's candidate . Capriles , 40 , represents a coalition of opposition parties . Capriles is the former governor of Miranda state . He lost to Chavez in October 's presidential vote , coming within 10 percentage points of the longtime leader . It was a significant gap , but the closest any opposition candidate ever came to defeating Chavez during his rule . More than 18.9 million Venezuelans are registered to vote in the presidential election . More than 68 % of the country 's registered voters had cast ballots by 3 p.m. Sunday , elections officials said . Far beyond Venezuela 's borders , voters lined up at diplomatic offices around the world . Venezuela 's National Electoral Council says that more than 100,000 Venezuelans are registered to vote abroad at diplomatic offices in 88 countries . There are more than 37,681 Venezuelans registered to vote in the United States , according to government figures . By midafternoon , thousands had cast ballots in New Orleans . Many said they had traveled by car or bus for more than 12 hours to get there from Florida because Venezuela shut down its consulate in Miami last year . Beatriz Olavarria , who worked to mobilize voters , said it was n't easy . While campaigning lasted for months before October 's election , this time around , the official campaign period was only a matter of days . `` It was much more difficult because the time has been short , and the budget has been low , '' she said Sunday , `` but the excitement has been enormous . '' In addition to representatives from national organizations serving as observers , Venezuela 's National Electoral Council says 170 foreigners have been invited to witness the elections in Venezuela . The international group includes delegations from the Union of South American Nations and the Atlanta-based Carter Center . Authorities detained 43 people Sunday for alleged electoral crimes , Maj. Gen. Wilmer Barrientos told reporters . But elections officials said Sunday evening that the day had proceeded smoothly without major incidents . `` It has developed with total normalcy , with total calmness , '' said Sandra Oblitas of the National Electoral Council . Polls were scheduled to close at 6 p.m. ( 6:30 p.m . ET ) , but Barrientos said polling stations where voters remained in line would remain open until the last voter cast a ballot . As polls were closing on Sunday evening , Twitter accounts for Maduro and his party were apparently hacked with posts denouncing `` electoral fraud . '' A group calling itself Lulz Security Peru claimed responsibility , while officials from Maduro 's campaign criticized what they said were `` dirty tactics , '' blaming right-wing political opponents for the hacking . Both candidates ' campaigns called on Venezuelans to await official results calmly earlier Sunday . But they also appeared to be bracing for a fight , with opposition leaders decrying what they said were election irregularities and Maduro 's campaign vowing to defend the election results . Capriles said in a Twitter post that some officials want to change `` the desire expressed by the people . '' Jorge Rodriguez , the head of Maduro 's campaign , stressed that the election had been fair and called on Maduro 's supporters to gather in front of the presidential palace . `` We will recognize the results , whatever they are , '' he said . `` And in this we say , that in the scenario that the anti-Chavista candidate wins by one vote , we will recognize it , but in the scenario that we win by at least one vote , we are going to defend this victory with the people of Venezuela . '' CNN 's Fernando del Rincon , Patricia Janiot and Paula Newton contributed to this report from Caracas . CNN 's Gustavo Valdes contributed to this report from New Orleans and CNN 's Claudia Dominguez contributed from Atlanta .
NEW : Capriles demands a recount . Election officials say Maduro won the vote . Twitter accounts for Maduro and his party are hacked . Official : " The election is over!