Toulepleu, Ivory Coast (CNN) -- Clashes along Ivory Coast's border with Liberia led thousands of people to flee their villages Tuesday, officials said. The confrontations occurred four days after seven U.N. peacekeepers and four civilians were killed in an ambush in the same area.
An armed group initiated an assault before dawn Tuesday on the village of Sioblo-Oula near the larger town of Tai, killing at least four civilians, wounding three and kidnapping two, said Tai's youth president, Toubate Darius.
The national army, FRCI, sought to protect them.
Tai Mayor Tere Tehe said one FRCI soldier was killed in the clashes, which lasted for 12 hours before ending Tuesday afternoon.
Tehe said hundreds of displaced people had arrived in Tai, where some of them sought shelter in the city hall. Others had fled to the forest, he said.
The Liberian border has been officially closed since June 10, but "the border in this region is porous," said FRCI Commander Aboubakar Sangare, in Toulepleu.
The movement began after blue-helmeted peacekeepers, who were in the area as reinforcements because of threats against civilians, came under attack last week.
U.N. Secretary-General Ban Ki-moon on Friday called on the government of Ivory Coast "to do its utmost to identify the perpetrators and hold them accountable." He added that he understood other peacekeepers remained in danger.
A spokeswoman for the U.N. mission in Ivory Coast said Friday's incident was the first attack on peacekeepers since they entered the country in 2004.
Sylvie van den Wildenberg, in a telephone interview from her office in Abidjan, said the remaining forces were continuing to protect area residents, "who are living in a very difficult terrain -- their villages scattered."
Van den Wildenberg said it was not clear who was responsible for the attack. "This is an area where you have so many different types of armed people," she said. "People have different aims and different reasons to carry arms and to perpetrate attack. So this is a very complex environment. We can't extrapolate. We just can't fingerpoint any group."
The peacekeepers were on a reconnaissance patrol because U.N. officials had heard rumors several days earlier of armed men in the area threatening to attack a village, she said.
U.N. peacekeepers remained in Ivory Coast after the 2010 presidential election, when the country was thrown into crisis after incumbent President Laurent Gbagbo refused to acknowledge defeat to former Prime Minister Alassane Ouattara. The latter was sworn in on May 21.
Western Ivory Coast has been largely supportive of Gbagbo. During the post-election crisis, his supporters massed heavy weapons here.
According to the United Nations, its peacekeeping force in Ivory Coast as of April 30 included nearly 11,000 uniformed personnel, as well as several hundred international civilian personnel, local staff and volunteers. They provide technical, logistical and security support to the government.
Authorities in the area have blamed the violence on militia supporters of Gbagbo based in Liberia but officials with the U.N. peackeeping mission in Ivory Coast have said they do not know whom to blame.
Gbagbo has been in custody at the Hague, accused of crimes against humanity during the post-election violence, in which thousands of people were killed.
Also Tuesday, the International Criminal Court at the Hague postponed a hearing for Gbagbo that had been scheduled for June 18. No new date was set.