A policeman went on a shooting spree killing four of his colleagues before being gunned down by soldiers in the southwest of Afghanistan, a provincial governor said on Sunday.
In an incident officials say they believe to be unrelated to the country's spiralling Taliban insurgency, the officer began shooting on Saturday night in Nimroz province.
"Last night, in Khashrod district, a policeman had an argument with his colleagues, he opened fire and killed four of them," provincial governor Ghulam Dastagir Azad told AFP.
"Then he took a civilian car and left. He drove to the neighbouring Dilaram district where he crossed an Afghan army checkpoint. He didn't stop and the soldiers shot (at) him.
"He returned fire and wounded a soldier before getting killed."
Azad said investigators thought it unlikely that the officer was a member of the Taliban, whose uprising has become increasingly virulent in recent years, especially in neighbouring Helmand province.
"We don't believe he was with the Taliban because he didn't steal the weapons of the policemen he killed and he didn't steal a police car but a civilian one.
"He was from Logar province and we believe he was not mentally fit. We're investigating the incident."
In early November an Afghan policeman killed five British soldiers who were mentoring him in Helmand province, in an attack later claimed by the Taliban.
Afghan police are on the front line in the war against the Islamist movement, with large numbers killed or maimed in the uprising.
Despite their key strategic importance for the Afghan government and its international backers, the force is poorly paid, badly equipped and suffers from high levels of corruption and drug addiction, observers say.
Afghanistan is fighting an increasingly difficult battle against the Taliban and its allies with the help of more than 100,000 US and NATO troops.
This year has been the bloodiest for international troops, Afghan soldiers and police and civilians since an international ouster of the Taliban in 2001.