Haiti's election results triggered protest that close the country's only international airport after the U.S. expressed worry that the results were "conflicting" with those of foreign observers.

Michel Martelly, who finished in 3rd place, vowed to contest results on alleged vote rigging following ruling party candidate Jude Celestin beat him by less than one percent in the 1st vote since January’s earthquake that killed up to 300,000.

Celestin goes on to a Jan. 16 2nd round vote against front- runner and former first lady Mirlande Manigat.

"The street are going up in flames," Damian Merlo, movement manager for Martelly, said in a phone interview from the capital, Port-au-Prince. "Clearly, the election was ridden with fraud."

Rioters threw rocks and clashed with UN international relations forces in the capital and attacked the headquarters of the ruling party, UN police spokesman Jean Francois Vizena said by phone. UN police were trying to confirm news of at least 2 deaths in southern Haiti as protests spread nationwide, he said.

"It's your right to protest, but do not attack public buildings, businesses and private property," President Rene Preval told protesters in a national radio address.

American Airlines cancelled its flights for today and tomorrow into Port-au-Prince as roadblocks obstructed personnel and passengers from reaching the airport, spokeswoman Martha Pantin said in a phone interview.

Manigat received 31.37 percent of votes, Celestin, a protege of Preval, received 22.48 percent and Haitian pop star Martelly 21.84 percent, according to preliminary results published by Radio Metropole.

The 2nd round will be held next month even as the country battles a spreading cholera epidemic that has killed 2,120 and hospitalized more than 44,000, according to Haiti's Health Ministry.