Afghan National Army soldiers (ANA) patrol at Nahr-e- Kanjak village at Adraskan district of Herat Province on Thursday. The Afghan presidential elections will be held on April 5. Photo: Reuters
Two female foreign journalists have been shot by a police officer in eastern Afghanistan, officials say.
One of the women died, the other was critically wounded in the attack. Both of the reporters worked for the Associated Press news agency.
The attack took place in the town of Khost near the border with Pakistan.
It comes as Afghanistan intensifies security ahead of presidential elections on Saturday, in response to threats of violence by the Taliban.
The new president will succeed Hamid Karzai, who has been in power since the 2001 fall of the Taliban but is constitutionally barred from seeking a third consecutive term.
Associated Press photographer Anja Niedringhaus, 48, was killed instantly in the attack, the news agency confirmed.
Veteran reporter Kathy Gannon, 60, was said to be in a stable condition and receiving medical treatment.
They came under attack whilst sitting in a car in a convoy protected by Afghan soldiers and police.
The last tweet sent from Anja Niedringhaus' Twitter profile was in condolence of another reporter killed away from home.
The two journalists had been visiting Tanay district in Khost province with an official from the Independent Election Commission, an interior ministry source earlier told the BBC.
The district lies on the border with Pakistan's Waziristan region, with the Pakistan-based Haqqani network strong and influential in the area.
The police officer behind the attack is currently being questioned in custody, the source said.
The Taliban has stepped up its attacks in recent weeks, in a bid to disrupt preparations for the election.
Last month, a senior reporter for Agence France-Presse, Sardar Ahmad, was killed alongside eight other people when Taliban gunmen attacked a hotel, which was popular with foreigners, in the Afghan capital of Kabul.
A journalist with Swedish and British nationality, Nils Horner, was shot dead in Kabul by gunmen on 11 March.
The BBC's Lyse Doucet in Kabul says the run-up to this historic poll has already been the bloodiest, and fears of electoral fraud are pronounced.
Nearly 200,000 troops have been deployed across the country to prevent attacks by the Taliban.
Rings of security have been set up around each polling centre, with the police at the centre and hundreds of troops on the outside.
The BBC's Afghanistan correspondent David Loyn says the election is being protected by the biggest military operation since the fall of the Taliban.
Reporting restrictions are in place, limiting what can be broadcast about the candidates.
If nobody wins more than 50% of the vote in this round, a run-off election will be necessary.
There are eight candidates for president, including former Foreign Ministers Abdullah Abdullah and Zalmai Rassoul, and former Finance Minister Ashraf Ghani Ahmadzai.
Correspondents say the election may give the US a new chance to repair relations with Kabul, which are moribund after more than 12 years of war and repeated rows between the White House and President Karzai.
Relations between the president and Washington plunged to new lows late last year when the Afghan leader refused to sign a bilateral security agreement that would allow up to 10,000 troops to stay in his country after the Nato combat mission ends.