Polls are open across Afghanistan and millions of voters are expected to choose a new president, as NATO tries to prevent insurgent attacks from disrupting the election.

Hamid Karzai is hoping win another term in office, but he is among 36 official candidates for the presidency.

His closest rival is Abdullah Abdullah, Karzai's former foreign minister. Election results are expected by Saturday evening.

Voting has started just one day after militants unleashed a deadly wave of violence, killing election workers and leaving six U.S. soldiers dead.

Two U.S. soldiers were killed by gunfire in the south, the military said, and a third was killed in an unspecified hostile attack. Two others died in a roadside bomb attack, and another died of non-combat injuries.

The six election workers were killed in the countryside, as the Taliban carried out its pledge to violently disrupt the election.

A remote-control bomb targeted a vehicle that was transporting election materials to the Chaparhar district of the eastern province of Nangarhar, early Wednesday morning. The driver was wounded, though the election materials were not damaged, said Ahmad Zia Abdulzai, a spokesperson for the province's governor.

Kabul was also rocked by violence Wednesday, when three insurgents took over a bank in the early morning.

Police exchanged gunfire with the militants for hours, while they surrounded a Pashtani bank branch located in a part of Kabul's old city. Fortunately, few civilians were in the area on a day which recognizes Afghanistan's independence from British rule.

Eventually, police stormed the building and killed three "terrorists," said Abdul Ghafar Sayedzada, the head of Kabul's criminal investigations unit.

Authorities put the gunmen's bodies on display for the media.

In other violence seen across Afghanistan on Wednesday, a roadside bomb in Uruzgan province killed three policemen, and a separate roadside bomb killed a district government leader and a tribal elder in the Registan district of Kandahar.

That followed two suicide car bomb attacks in the past four days and a rocket attack on central Kabul in recent days. Six election workers were killed on Tuesday alone.

The Afghan government has asked the media to censor reports of violence on election day, but both local and international news organizations say they will report as normal.

The Foreign Ministry issued a statement saying the media should avoid "broadcasting any incidence of violence between 6 a.m. and 5 p.m. on election day to "ensure the wide participation of the Afghan people."

The English release "requested" the ban but the version in the local Afghan dialect of Dari said broadcasting any incidence of violence was "forbidden."

Afghan's local media has condemned the government's statement, saying it was stifling the freedom of the press that was supposed to occur after the fall of the Taliban.

"We will not obey this order. We are going to continue with our normal reporting and broadcasting of news," Rahimullah Samander, head of the Independent Journalist Association of Afghanistan, said.

Even dangerous in Kabul

CTV's South Asia Bureau Chief Janis Mackey Frayer said the persistent level of violence in the lead-up to the election has been highly disruptive to life in Kabul.

"There seems to be a sense of lockdown in Kabul, which is already a heavily fortified city," Frayer said when speaking to CTV's Canada AM from Kabul on Wednesday morning.

"Many civilian employees of the military agencies here are being told that they must stay indoors, NGOs are telling their workers the same thing...and many Afghans are choosing to stay at home because of what has been a wave of violence over the last number of days."

She said that the Taliban was making specific threats against Kabul.

"The Taliban warned it already had 20 suicide bombers waiting on the street of Kabul for election day," she told Â鶹´«Ã½ Channel Wednesday.

"There is certainly a chill running through certain parts of this country that may keep voters at home," she said.

While Afghan police were able to end the standoff at the Pashtani bank without harming any civilians, the incident was another reminder of what could happen on Thursday.

"It's the message that it sends and the message that the Taliban wants to get across, which is that it will use a range of tactics to disrupt the election tomorrow," Frayer said.

That very same message concerned Kabul shopkeeper Abdul Jalal, one of the few civilians who present when the bank was taken over by militants on Wednesday morning.

He said that if the violence continued, he and his wife would stay home on election day.

"Tomorrow, we plan to go to the polling centre," Jalal said. "But if it was like today, we will not vote. Elections are a good thing for Afghanistan, but security is more important."

Election facts and figures

  • 17 million out of an estimated 30 million Afghans are registered to vote.
  • The minimum voting age is 18.
  • There are approximately 7,000 polling centres across Afghanistan though officials concede 'hundreds' may not open because of security threats.
  • Ballots will be counted at each polling centre as soon as voting ends.
  • Counting could take two to three weeks but preliminary results could be revealed as early as late Saturday.
  • Only when the Electoral Complaints Commission has cleared all 'priority; complaints will the results be certified by the Afghan Independent Election Commission.
  • The final results will be declared on 17 September.
  • If there is a run-off vote it will likely begin early October.

With files from The Associated Press