Port-au-Prince , Haiti ( CNN ) -- Riot police fired tear gas and sent hundreds of demonstrators running a day after Haiti 's national elections ended in turmoil amid allegations of widespread fraud . The incident took place as one of the 18 presidential candidates was denouncing the outgoing president and his endorsed candidate in a news conference broadcast live on Haitian radio . `` I have a message for [ Rene ] Preval and his acolyte , '' said Michel `` Sweet Mickey '' Martelly . `` Haiti does n't want you any more . '' As he spoke , hundreds of people , chanting Martelly 's name , jogged toward the center of Port-au-Prince until they were intercepted by riot police . The tide turned when police fired several canisters of tear gas into the crowd , sending Martelly 's supporters sprinting for cover . On Sunday , hours before the polls closed , Martelly and 11 other candidates for president made a joint declaration denouncing the election and calling for its cancellation . The candidates accused Preval of organizing widespread fraud in favor of his Unity Party , which is fronted by establishment candidate Jude Celestin . The dissenting candidates did not offer evidence to back up their claims . Senior officials from Haiti 's election organizing committee , the Conseil Electoral Provisoire , defended the vote and calling it a success . `` The election day has successfully concluded , '' said the committee 's director general , Pierre Opont , in a news conference Sunday night . Opont said there had been incidents at 56 polling centers out of a total of 1,500 across the country , less than 4 percent . He also said at least one person died as a result of election violence . However , there were widespread reports Sunday of disorganization and some cases of apparent cheating at the polls . `` We had observers in about 50 polling stations , and in each one we interviewed countless individuals who could not vote at that polling station because their names were n't on the electoral lists , '' said Nicole Phillips , staff attorney with the non-profit organization Institute for Justice and Democracy in Haiti . `` If we go ahead and certify the elections , '' Phillips said , referring to international donors that have helped fund the vote , `` then we look bad . We paid for these elections . We organized them . We trained the people . And the fact that it was horrible yesterday looks bad on us . '' On Sunday , the United Nations issued a written statement expressing `` deep concern at the numerous incidents that marred the elections . '' A spokesman for the U.S. Embassy in Port-au-Prince said American diplomats were appealing for calm and waiting for the result of a report expected to be issued by a team of international election observers in a joint delegation from the Organization of American States and the Caribbean Community . Ambassador Colin Granderson , head of the monitoring delegation , Monday listed a large number of irregularities and problems with the election . However , he said , `` the joint mission does not believe that these irregularities , serious as some of them were , necessarily invalidate the process . '' He called the decision of the 12 presidential candidates to call for cancellation of elections hours before polls closed `` precipitous '' and `` regrettable . '' He said the vote-counting process should continue , and made a fresh appeal for calm among all parties . In addition to the presidential election , seats also were being contested in the Senate and in the lower house of parliament . Nearly all of the candidates campaigned on similar platforms -- fighting corruption , creating jobs , and addressing a series of natural disasters that has left the Caribbean nation reeling and prompted many to urge for a postponement of Sunday 's vote . According to electoral law , a candidate must win 50 percent of the vote or the election goes to a second-round runoff . Haiti 's growing political crisis comes as it struggles to cope with a deadly cholera epidemic that has killed more than 1,600 people since last month . On Monday , the turmoil appeared to be spilling over the border . A United Nations Police spokesman confirmed reports of a clash erupting on Haiti 's border with the Dominican Republic between soldiers of that nation and Haitian civilians . `` Shots were fired , '' said spokesman Jean-Francois Vezina . `` Our UNPOL people are there and trying to intervene . '' Vezina said he could not confirm reports broadcast on Haitian radio that a woman and a girl were killed in the border clash .
Riot police fire tear gas at demonstrators after Haitian candidate 's speech . 12 of the 18 presidential candidates are alleging widespread fraud at the polls . An international monitoring official says vote-counting should continue .