An Afghan police officer fatally shot 11 of his colleagues as they slept at a checkpoint in the southern province of Helmand, officials have said.
Omer Zwak, a spokesman for the provincial governor, said the officer turned his rifle on fellow police in the attack late on February 27 in Lashkar Gah, the provincial capital.
Zwak said the attacker seized his victims' guns and ammunition and fled the scene in a police vehicle -- presumably to join the Taliban, which claimed responsibility for the attack.
"Insider" attacks in which Afghan soldiers and police turn their guns on their colleagues or on international troops have been a major problem during the 15-year-old war in Afghanistan.
Afghan security forces battling a resurgent Taliban are struggling to tackle such incidents as they also face record-high casualties and mass desertions.
Lashkar Gah is one of the few areas in Helmand currently held by the government.