Protesters enraged by the results of Haiti's troubled presidential election have set up barricades and political offices ablaze, traded blows with UN peacekeepers and shut down the country's lone international airport, creating the social upheaval many have feared since the January 12 earthquake.
The fallout from the disputed November 28 election is violently shutting down cities across the impoverished country with gunfire and barricades at a moment when medical aid workers need to tackle a surging cholera epidemic that has claimed more than 2,000 lives.
Thousands of people took to the streets of the capital, erecting barricades and setting fires, furious that government-backed candidate Jude Celestin, the protege of unpopular President Rene Preval, apparently will go on to a runoff vote while carnival singer Michel "Sweet Micky" Martelly finished third in official results and is probably eliminated.
Flames leapt from the roof of the Unity party headquarters, the centre of Celestin's campaign. Witnesses said the building in central Port-au-Prince was on fire for an hour.
Protesters say security guards shot at demonstrators as they assaulted the building. Several fire trucks were trying to control the blaze, an unusual scene in a city with few reliable public services.
Protests have also broken out in Les Cayes, Cap-Haitien and other cities. Groups of young men armed with clubs and sticks marched through the streets to government buildings, electoral offices and foreign embassies.
Thousands of voters were disenfranchised by confusion on the rolls and there were many reported incidents of ballot-stuffing, violence and intimidation confirmed by international observers.
Turnout was low according to the preliminary results, as just over one million people cast accepted ballots out of some 4.7 million registered voters. It is not known how many ballots were thrown out for fraud.