Five main candidates are standing in Colombia's first elections since the peace deal to end a half-century of conflict. Hard-line conservative Ivan Duque led the opinion polls, but is expected to fight a second round.
Polls have closed in Colombia's presidential election, the first round in the contest to replace current president Juan Manuel Santos. If no candidate gains more than 50 percent of the vote, the top two will compete in a runoff on June 17.
The 41-year-old Ivan Duque, a conservative former senator, led in public opinion polls but was not expected to win the necessary majority in the first round. He is a protege of influential former President Alvaro Uribe, who is a leading critic of the peace agreement.
"I want a country of legality, a full-on fight against corruption, a country where peace can breathe throughout the land," Duque said after voting in Bogota on Sunday.
Duque has vowed to alter the terms of the peace deal and to jail former rebels for war crimes.
His main challenger is the 58-year-old leftist Gustavo Petro, who was once mayor of Bogota and a former member of the M-19 guerrilla group in the 1980s.
Petro has pledged to lead the country away from its dependency on oil exports, while ramping up agricultural production by redistributing wealth from the rich to the poor.
At least two other candidates are thought to be within striking distance of the coveted number two spot, including former Medellin Mayor Sergio Fajardo and former Vice President German Vargas Lleras.
The candidates are vying to replace the outgoing Santos, who won the Nobel Peace Prize for ending the five-decade-old insurgency that left more than 30,000 people dead.
The new president will take office in August.
bik/jm (AP, Reuters, AFP, dpa)