Port-Au-Prince, Haiti (CNN) -- Voting in the second round of Haiti's presidential runoff was mostly calm Sunday, although two shooting deaths were linked to election violence, according to the head of Haiti's national police.
Some irregularities and shortages of election materials were resolved and voters were given an extra hour to cast ballots, the electoral council said.
A police officer was arrested in Port-de-Paix Sunday morning because he was telling people how to vote, according to Mario Andresol, the head of the national police.
Andresol offered no detail on the shootings that he said were election related.
Haitians are choosing between a former law professor and first lady Mirlande Manigat and singer Michel Martelly in a pivotal presidential runoff vote for a nation still recovering from a devastating earthquake and political turmoil.
Final results of the runoff will be released April 16, according to officials.
Martelly made a name for himself as a flamboyant carnival musician who sometimes ripped his clothes off onstage.
In early December, the electoral council announced that Manigat had won but lacked the majority of votes needed for an outright victory. Initial results put her in a runoff with government-backed candidate Jude Celestin.
Haitians responded by charging fraud and burning cars, tires and Celestin's campaign headquarters in Port-au-Prince.
The third-place candidate, Martelly, claimed he had won more votes than Celestin and a review of results by an Organization of American States team supported that contention.
The review suggested that Martelly earned a spot in the runoff.
The reappearance of a political heavyweight and former president, Jean-Bertrand Aristide, has sparked concerns of more political turmoil.
Aristide, who has been living in exile in South Africa for seven years, returned last week. U.S. officials expressed concern over his return, saying that his presence would prove destabilizing.
But Aristide's lawyer has said he has no intention of getting into politics.
Haiti has been struggling to recover since a massive earthquake struck more than a year ago. Its troubles were compounded by a cholera outbreak that killed thousands, and the turmoil surrounding the November 28 presidential election.
Meanwhile, the publicist for Haitian-born hip-hop singer Wyclef Jean said Sunday that the artist was shot in the hand in the capital Port-au-Prince Saturday, but was treated and released from the hospital.
"He is doing well," Cindy Tanenbaum said, calling the wound superficial.
Jean, a Haiti native, tried to run for president himself but was ruled ineligible by election officials.
CNN's Deborah Doft and journalist Allyn Gaestel contributed to this report.