Akhir 27, 1432H/ April 1, 2011, SPA -- Eight foreign United Nations staff and five Afghans were killed Friday after a peaceful protest turned violent in the northern Afghan province of Balkh, officials said according to dpa. Friday's event was initially peaceful, but suddenly turned violent when the demonstrators reached a United Nations compound, Munir Ahmad Farhad, spokesman for the provincial governor said. Police said that the protesters overwhelmed the security guards of the compound and then barged in, torching the office and throwing stones at police forces who arrived at the scene to control the mob. Lal Mohammad Ahmadzai, police spokesman for police forces in the region said that the eight foreigners were killed as the protesters attacked an office for the UN Assistance Mission for Afghanistan. "They were foreigners, because the Afghan UN workers were off because of Friday holiday," he said. Investigation was opened into the incident, the spokesman added.