Taliban threats scared voters and dampened turnout in the militant south Thursday as Afghans voted for president for the second time ever. Insurgents killed 26 Afghans in scattered attacks, but officials said militants failed to disrupt the vote.

After 10 hours of voting, including a last-minute, one-hour extension, election workers began to count millions of ballots. Initial results weren't expected for several days.

A top election official told The Associated Press he thinks 40 to 50 percent of the country's 15 million registered voters cast ballots — a turnout that would be far lower than the 70 percent who cast ballots for president in 2004.

Low turnout in the south would harm President Hamid Karzai's re-election chances and boost the standing of his top challenger, former Foreign Minister Abdullah Abdullah. Turnout in the north appeared to be stronger, a good sign for Abdullah.

International officials have predicted an imperfect election — Afghanistan's second-ever direct presidential vote — but expressed hope that Afghans would accept it as legitimate, a key component of President Barack Obama's war strategy. Taliban militants, though, pledged to disrupt the vote and circulated threats that those who cast ballots would be punished.

A voting official in Kandahar, the south's largest city and the Taliban's spiritual birthplace, said voting appeared to be 40 percent lower than 2004. The official asked not to be identified because he wasn't authorized to release turnout figures. Associated Press journalists reported low turnouts in Kabul compared with longer lines seen in the 2004 vote.

"In the early morning, the turnout was slow, particularly in the south of the country, but in the middle of the day, it turned out to be very good," said Zekria Barakzai, Afghanistan's deputy chief electoral officer. "In central and some northern provinces, the turnout was huge."

Security companies in the capital reported at least five bomb attacks, and Kabul police exchanged fire for more than an hour with a group of armed men; two suicide bombers died in the clash, police said. Taliban spokesman Zabiullah Mujahid claimed that five gunmen were fighting with police.

Karzai, dressed in his traditional purple-and-green-striped robe, voted at a Kabul high school. He dipped his index finger in indelible ink — a fraud prevention measure — and held it up for the cameras. Presidential aides released a rare photo of Karzai's wife casting her vote.

After polls closed, Karzai complimented Afghans for having the courage to vote and brushed aside questions about turnout.

The Afghan people braved "rockets, bombs and intimidation and came out to vote. We'll see what the turnout was, but they came out to vote. That is great," Karzai said.

The president said militants carried out 73 attacks in 15 provinces — a 50 percent increase in attacks compared with recent days, according to NATO figures. Karzai's ministers of defense and interior said attacks killed eight Afghan soldiers, nine police and nine civilians. A U.S. service member was killed in a mortar attack in the east Thursday, bringing to at least 33 the number of U.S. troops killed this month.

Karzai, who has held power since the Taliban was ousted in late 2001 by a U.S.-led invasion, is favored to finish first among 36 official candidates, although a late surge by Abdullah could force a runoff if no one wins more than 50 percent.

The next president will lead a nation plagued by armed insurgency, drugs, corruption and a feeble government. Violence has risen sharply in Afghanistan in the last three years, and the U.S. now has more than 60,000 forces in the country close to eight years after the U.S. invasion following the Sept. 11, 2001, attacks.

Karzai, a favorite of the Bush administration, won in 2004 with 55.4 percent of the vote, riding into office on a wave of public optimism. As the U.S. shifted resources to the war in Iraq, Afghanistan fell into steep decline, marked by record opium poppy harvests, deepening government corruption and skyrocketing violence.

The top U.N. official in the country, Kai Eide, acknowledged scattered attacks but said the election "seems to be working well." A U.N. spokesman said there were no early reports of widespread irregularities, though ahead of the vote the country had buzzed with rumors of ballot-stuffing, bogus registrations and trafficking in voter cards on behalf of Karzai — allegations his campaign has denied.

Presidential candidate Ramazan Bashardost, who had 10 percent support in pre-election polls, said he washed off the supposedly indelible ink and called on authorities to "immediately stop this election." Barakzai said that if election workers did not shake the ink beforehand it could be wiped off, and that officials fixed the problem early. He said the problem was not widespread.

Militants carried out a string of assaults around the country. In northern Baghlan province, insurgent attacks closed 14 polling sites, and the police chief of Old Baghlan city and several police were killed, said Abdul Malik, the provincial election director. Five Afghan troops died in eastern Khost province.

An AP reporter in southern Helmand province said more than 20 rockets had landed in the capital of Lashkar Gah, including one near a line of voters that killed a child.

A blast at a high school in Kabul serving as a polling center wounded an election monitor and briefly shut down voting, an election observer named Ezatullah said. Abdullah Azizi, a 40-year-old teacher, said he was at Abdul Hai Habibi school when the explosion occurred.

"We don't care about these blasts," Azizi said after voting reopened. "The women were afraid when they heard the explosion, but now I'm going to tell them come here."

Barakzai said that 6,202 polling centers opened, 95 percent of those officials had planned to open. He said he thinks that 40 percent to more than 50 percent of the country's registered voters cast ballots. Just over 8 million cast ballots in 2004.

The Foreign Ministry asked news organizations to avoid "broadcasting any incidence of violence" during voting, and Afghan officials appeared reluctant to confirm violence, but the order did not significantly affect the flow of information during the day.

In the Helmand province town of Dahaneh — a former Taliban stronghold until U.S. troops invaded this month — U.S. Marines delivered presidential ballots in two helicopters just after noon. Fifty of 74 registered voters cast ballots.

Voter turnout in the insurgency-plagued Pashtun south is not only crucial to Karzai's chances but also to public acceptance of the results. Karzai is widely expected to run strong among his fellow Pashtuns, the country's largest ethnic group that also forms the overwhelming majority of the Taliban.

Karzai has sought to ensure his re-election by striking alliances with regional power brokers, naming as a running mate a Tajik strongman and welcoming home notorious Uzbek warlord Abdul Rashid Dostum.

Abdullah, who is part Tajik, is expected to win much of his votes in the Tajik north, where security is better.