KABUL -- Polls have closed in Afghanistan's presidential election with voting marred by several attacks and reports of problems at polling stations.
Fifteen candidates were on the ballot, but the race was widely seen as a two-horse race between President Ashraf Ghani, who is seeking another five-year term, and Chief Executive Officer Abdullah Abdullah.
Soon after polls opened across the country earlier on September 28, officials in the southern city of Kandahar reported an explosion at a mosque serving as a polling station. Local hospital officials later said at least 15 people had been wounded in the blast, three seriously.
In response to a spate of Taliban attacks in recent weeks, the government has bolstered security to try to ensure what could be the second-ever democratic transition of power in the war-wracked country of 35 million people.
Some 72,000 security personnel were deployed to secure polling centers across the country, which opened at 7 a.m. and were originally scheduled to close at 3 p.m., but the Independent Election Commission later extended voting by two hours until 5 p.m.
WATCH: Afghanistan Holds Presidential Election Amid Attacks
The Independent Election Commission (IEC) said early on September 29 that the 1 million votes counted so far had been tallied across 2,597 polling stations -- just over half of the total number of polling stations that remained open for the vote. Afghan election officials said polling took place in a total of 4,905 centers. More than 500 polling stations were closed due to the threat of militant attacks.
Election officials did not immediately share the details on turnout but observers from the Afghanistan Independent Human Rights Commission said turnout appeared to be low, especially among women.
Besides the attack in Kanadahar, there were also reports of sporadic rocket attacks elsewhere in the country on September 28.
And Reuters reported that explosions also hit the Afghan cities of Kabul, Ghazni and Jalalabad.
Later reports spoke of insurgents firing mortars on the northern city of Kunduz.
Ghulam Rabani Rabani, a council member for Kunduz Province, said Taliban militants had also attacked Afghan security forces in two locations outside the city, in running gun battles.
Officials said five security officials had been killed in the attacks and 37 civilians wounded.
"The enemy carried out 68 attacks against election sites across the country... but security forces repelled most of the attacks," Acting Defense Minister Asadullah Khalid said.
Around 9.6 million Afghans were registered to vote in the election, the fourth presidential vote since the U.S.-led invasion toppled the Taliban in 2001.
Yousef Rashid, the head of the Free and Fair Election Forum of Afghanistan, said earlier in the day that voting was generally smoother than in the past, but difficulties had been reported across the country, including problems with the biometric voting devices that are meant to combat voter fraud.
“At some polling stations the voting process has started late, and the biometric system still has a problem, but if we compare it with the previous election these problems are less,” Rashid told RFE/RL's Radio Free Afghanistan.
Mohammad, a voter in the capital Kabul, complained his name was not on the local voter list.
“I have come here [polling station] with my original national ID card, but they cannot find my name in the voter registration list. I do not know what to do,” he said.
Ghani, 70, and Abdullah, 59, have led a deeply unpopular and fractured national-unity government since a U.S.-brokered power-sharing agreement following a disputed, fraud-marred presidential election in 2014.
A Pashtun, Ghani is from the largest ethnic group. He is a Western-educated technocrat who has served as finance minister. Abdullah, a trained ophthalmologist, was a senior member of the anti-Taliban Northern Alliance and has support among ethnic Tajiks, the country’s second-largest group.
Other high-profile candidates include former intelligence chief Rahmatullah Nabil and Gulbuddin Hekmatyar, the notorious former warlord and militant leader.
The factors underlying the fraudulent elections in 2014 -- systemic corruption, widespread political and economic insecurity, and a problematic electoral system -- have not been addressed and many observers have warned of another potential dispute.
That scenario could ignite a protracted political crisis and raise the threat of civil war in the multiethnic country.
WATCH: Young Afghans Raised After Taliban Rule Go To Polls
Observers say the fear of violence and the potential of another disputed election have sapped enthusiasm for the vote, with some expecting record-low turnout.
In 2014, turnout was nearly 60 percent, while only 38 percent of eligible voters cast ballots in chaotic parliamentary elections in October last year that were marred by technical and organizational issues.
If no candidate receives a majority in the first-round vote, a second round will be held on November 23 between the top two finishers.
Preliminary results for the September 28 vote are expected on October 19, allowing electoral bodies to process complaints and tally votes sent to Kabul from remote areas of the mountainous country.
The final results are expected to be announced on November 7.