After decades of war, Southern Sudanese turned out in triumphant droves in this future capital city on Sunday to begin voting on whether to declare independence, but clashes along Sudan's disputed north-south border put a damper on the otherwise joyful celebrations.

At least nine people had died by late Saturday in fighting that has raged for three days in Abyei, a key border area, officials confirmed Sunday.

In Southern Sudan's capital, Juba, the first day of the weeklong voting process was peaceful and orderly. Lines outside polling stations reached into the thousands as people snaked through open yards and poured into the street.

"This is what we fought for," said Joseph Chunduk, a 36-year old former rebel dressed in civilian clothes and hundreds of people back from the front of the line despite arriving at 3 a.m. "I'm standing here for my freedom."

The polling centers buzzed with excitement. Some voters camped overnight to be first in line. Young people danced and waved the southern flag. Some voters pumped their fists emphatically into the air after casting their ballot.

"The people have been quite peaceful, and apparently very happy," former U.S. President Jimmy Carter, whose Atlanta-based Carter Center is observing the referendum, said in Juba on Sunday .

Carter said he foresaw no problems that would threaten the integrity of the final outcome. The vote is expected to go overwhelmingly in favor of secession.

The ecstatic mood flows from a deeply scarred past. For 50 years, rebels in Sudan's south fought the country's central government in Khartoum the north. Two million people, primarily southern, are thought to have died in the conflict through violence, famine, and disease.

A 2005 accord brokered by the U.S. ended the war by promising Southern Sudan the referendum on secession following a six-year interim period.

Salva Kiir, Southern Sudan's leader, opened voting in the morning at a memorial for John Garang, who led the southern rebel Sudan People's Liberation Movement's until his death in a 2005 helicopter crash just months after signing the Comprehensive Peace Agreement. Kiir, his longtime deputy, took power after his death.

"I believe Dr. John and all those who died with him are with us today, and I must assure them that they have not died in vain," Kiir said after voting.

Abeyi was the only area where scheduled voting did not occur. The border area was designated as a special joint-administrative zone under the peace deal and was to decide in a special referendum whether to join north or south Sudan.

But a battle is raging over who can vote between Abyei's permanent southern community, the Ngok Dinka, and the Misseriya, a northern nomad group that uses the land for seasonal grazing, the Misseriya.

Abyei is the site of the last major clash between the northern and southern militaries in 2008, killing dozens and displacing tens of thousands.

According to a U.N. official, who spoke on condition of anonymity because he is not authorized to speak on the record on the matter, a band of Misseriya militiamen on Friday launched attacks on southern police posts that form a security cordon around Abyei town, which is inhabited by the Ngok Dinka.

The U.N. official said nine southern policeman died after three different clashes on Saturday and that fighting continued on Sunday near the village of Makier-Abior, though there were no resports of casualties.

Misseriya leaders deny blame for the skirmishes. The Agence France-Presse news agency quoted one Misseriya as saying the Dinka Ngok started the fighting by firing on Misseriya cattle as they tried to drink from a river.

"All sides should refrain from inflammatory rhetoric or provocative actions that could raise tensions or prevent voters from expressing their will," President Barack Obama said in a White House statement that congratulated Sudan for the start of the referendum.

"Violence in the Abyei region should cease," warned the statement.

Actor and activist George Clooney was also in Juba. "It's something to see people actually voting for their freedom. It's exciting to see," he said.

Clooney, who visited Abyei on Saturday, warned that the peace process could crumble if the dispute over the border region is not quickly resolved.

"Abyei is very unhappy and upset about what's going on," he said.