Afghan officials say a NATO helicopter mistakenly killed four Afghan troops in the east while a Taliban ambush left an official and three other people dead in the country's south. Spokesman Ahmad Zia Abdulzai says a NATO helicopter called in as air support following an attack on an Afghan checkpoint in eastern Nangarhar province's Bati Kot district accidentally killed four Afghan troops Wednesday night. A NATO spokesman, Sgt. Bryan Gatewod says the incident is under investigation, according to a report of the Associated Press. In southern Uruzgan province, spokesman Farid Ayel says the Taliban ambushed local education official Hadi Khan, killing him, his two sons and a bodyguard on Wednesday afternoon. In northwestern Faryab province, Governor Ahmadullah Batash says a roadside mine exploded on Thursday, killing two policemen and a prosecutor, and wounding seven people in Bilchiragh district.