An Afghan policeman killed 11 colleagues, including his commander, Saturday, just a day after six foreign troops were killed by their Afghan partners in two other incidents, dpa quoted officials as saying. The latest attack took place in a police station in Delaram district of western province of Nimroz. The gunman was also killed when other police returned fire. "We have sent an investigation delegation to the area," said Colonel Abdullah, the criminal investigation officer at the Nimroz police headquarters. On Friday, there were two incidents of Afghan colleagues shooting their foreign allies, in which a total of six NATO-led soldiers were killed - a significant rise in so-called green-on-blue attacks on foreign troops by their Afghans allies. An Afghan working for NATO-led forces shot dead three foreign soldiers late Friday in a joint military base in Garmser district of southern province of Helmand. A source, who was speaking to dpa on condition of anonymity, said the assailant may have been a civilian interpreter. But NATO officials did not confirm this. Another government official, however, said the killer was an Afghan police officer. Small units of foreign troops often share facilities with Afghan government and police officers.