JALALABAD, Afghanistan, July 1 (Xinhua) -- Militants of the Islamic State (IS) group brutally killed three staff of a local high school in Afghanistan's eastern province of Nangarhar overnight, the provincial government said on Sunday.

"The incident occurred in Malikyar High School in Khogyani district late Saturday night. The assailants also set on fire scores of books in a building after killing the unarmed men," the government said in a statement.

Provincial Governor Hayyatullah Hayyat has condemned the attack and ordered the security forces to arrest and bring to justice the perpetrators, according to the statement.

Since earlier this year, the security forces have been clashing with IS militants in Khogyani, southwest of provincial capital Jalalabad city. The clashes have forced thousands of villagers to flee.

The IS group, which emerged in Nangarhar in early 2015, has yet to make comments on the report.