Haitian presidential candidate Michel Martelly walks through traffic as he marches to the national palace in Port-au-Prince on Thursday. (Keith Bedford/Reuters)Shots were fired at people attending a rally held by Haitian presidential candidate Michel Martelly, and his campaign team is calling it an assassination attempt.

Martelly, one of the leading candidates and a popular singer in Haiti, was leaving his final campaign rally Friday evening in the seaside town of Les Cayes when shots were fired from a pickup truck. There are reports at least one person was killed and several were wounded.

Someone grabbed Martelly and moved him away, his cousin Richard Morse told reporters at a hotel in Port-au-Prince on Saturday. He said his group then heard machine-gun fire.

Later, the entourage all met up at a gas station. "When you're in this situation, you're acting and reacting," said Morse, adding he wasn't completely sure what happened.

Martelly campaign aide Karine Beauvoir said her group stands by its statement that this was an assassination attempt.

It was the second such recent incident. Mirlande Manigat, whose husband once served as interim president, cut her rally short two days ago after a gun was fired in the crowd.

The candidates and the United Nations are predicting more violence.

Edmond Mulet, head of the UN Mission in Haiti, has acknowledged that violence could erupt while people head to the polls, but he said in a statement earlier this week that security forces have been trained to provide safe conditions at polling stations.

Both Martelly and Manigat have accused the government of potential fraud in Sunday's vote, and another of Haiti's biggest parties is refusing to recognize the election at all.

Fanmi Lavalas, the party of former president Jean-Bertrand Aristide, was barred from the election. A party spokeswoman said the election is a masquerade, and the party views it as a selection, not an election.

The election comes as Haiti battles a growing cholera outbreak that has claimed more than 1,600 lives. It is also the first election since a 7.0-magnitude earthquake last January killed 250,000 people.

With files from CBC's Amber Hildebrandt