(CNN) -- Retired army Gen. Otto Perez Molina won Sunday's runoff presidential election in Guatemala, seizing on voters' concerns about growing insecurity in the Central American nation.
Perez Molina led with more than 53% of the vote, Guatemala's election authority said. His opponent, businessman Manuel Baldizon, garnered 46% of the vote.
"I want to tell you that we are happy, that we are very excited by this decision, but at the same time we have a big responsibility not to fail the Guatemalans in the next four years," Perez Molina told a crowd of cheering supporters.
Perez Molina said unity across party lines would be a key step in solving the country's security problems.
"Let's put these elections behind us ... and come together in the the things we have in common, to pull Guatemala out of this crisis that we are living," he said.
In Guatemala City Monday, Perez Molina's supporters celebrated the news.
"I am very happy because we are going to have a change in our country," Jazmin Dominguez said.
Perez Molina, a retired army general who pledged to take a tough stand on crime, was the front-runner heading into the election. He won the most votes in the first round of voting in September.
Low voter turnout was reported in Sunday's election, according to the state-run AGN news agency.
Concerns about violence in Guatemala, which has worsened as Mexican drug cartels have stepped up operations in parts of the country, dominated the vote.
In a Vox Latina national survey in July, more than two-thirds of Guatemalans said violence was what concerned them most, far outpacing the combined totals for the economy, unemployment, poverty and lack of education.
"Let's hope that it's not like it's been with the government in the past, that they aren't just lies. The truth is that it's important that we return our country to the right path. We need security, education, health. We really hope the new president does all this," Guatemala City resident Juan Diego said Monday.
Campaign posters for Perez Molina, who led in polls before Sunday's election, featured a clenched fist. The 60-year-old retired general pledged to bring a "mano dura" -- firm hand -- to Guatemala's highest office.
In a debate co-hosted by CNN en Español this year, Perez Molina called for "elite units of the army" to play a larger role in the nation's battle against gangs and drug cartels.
But that proposed approach -- and Perez Molina's high rank in the military during Guatemala's decades-long civil war -- worries human rights groups both in Guatemala and abroad.
Concerns stem from the fact that the Guatemalan military committed multiple atrocities during the civil war, though Perez Molina has never been directly implicated in any of them.
The former general campaigned for president a second time this year. He was defeated in 2007 by incumbent President Alvaro Colom.
First-time candidate Baldizon, 41, who ran under the banner of the Leader Party, energized young voters. He promised to continue social and economic programs that he warned would be at risk, if Perez Molina won. Like the former general, Baldizon championed a crime-fighting plan.
Poverty is endemic in Guatemala, and the country has one of the worst crime rates in Latin America. Forty-three percent of children under 5 are chronically malnourished. And the murder rate last year was 42 per 100,000 people -- one of the highest in the world.
While supporters praised his tough stance on crime, others said they feared the president-elect's platform did not adequately address poverty.
"I think that he is going to make a government of the rich. I do not think that they are thinking about the poor and they are going to leave us forgotten again," Guatemala City resident Nelson Guzman said.
This is only the fourth time that Guatemala has held presidential elections since peace accords were signed in 1996, officially ending a civil war that devastated the country for 36 years. The conflict left more than 100,000 people dead and a million refugees.
Perez Molina will take office in January.