Afghan voters are going to the polls Saturday to choose a new president amid heavy security.
Results are not expected for a few weeks. A second round may be needed if none of the eight candidates gets more than half the vote.
Security is tight across the nation because insurgents have promised to disrupt Saturday's vote. The lead-up to the vote has been fraught with violence.
Neighboring Pakistan has closed all border crossings with Afghanistan and deployed additional troops in an attempt to help Afghanistan conduct the election peacefully. Pakistan said the border security arrangements were stepped up in close coordination with Afghan security forces.
On the eve of the vote, one Associated Press journalist Anja Niedringhaus was fatally shot and another, Kathy Gannon, was wounded by a policeman, as they reported on election preparations in Afghanistan. Authorities say the police officer was arrested following the incident inside a heavily-guarded district compound in a remote part of the eastern province of Khost.
It was the third deadly attack against journalists in the past three weeks.
The Taliban has vowed to interfere with Saturday's presidential and provincial council vote.
Afghan President Hamid Karzai said he was grieved by the shooting of the journalists and ordered a full investigation.
The United Nations, Reporters Without Borders, and the Committee to Protect Journalists all condemned the attack and expressed their condolences. Paris-based press freedom group Reporters Without Borders said the shooting highlights the "permanent and ubiquitous danger" for reporters in some regions of Afghanistan and called on authorities "to do everything possible to guarantee the safety of journalists, whose role is crucial at the height of the electoral process."
On March 11, British-Swedish radio journalist Nils Horner was shot and killed at point-blank range on the streets of Kabul. Nine days later, gunmen shot and killed Afghan reporter for the French News agency Sardar Ahmad, as well as his wife and two of his three young children in Kabul's heavily protected Serena Hotel.
On Thursday, Jan Kubis, the U.N. Special Representative for Afghanistan, urged Afghan citizens not to let anyone deprive them of their right to vote.
Kubis said there might be difficulties and security problems, but Afghanistan is much better prepared for Saturday's election than it was in 2009.
The Taliban has claimed responsibility for recent election-related violence, including Tuesday's suicide bombing outside the Afghan Interior Ministry, killing at least six police officers.