An explosion rocked Khost city the capital of Khost province in east Afghanistan on Friday killing two people and injuring two others, an official said.

"It was a roadside bomb struck a vehicle of Afghan army in Khost city the capital of Khost province at 4:15 p.m. local time as a result two persons including an army soldier were killed," an officer with the Afghan army in Khost province Raz Mohammad Oryakhil told Xinhua.

Two more civilians sustained injuries in the blast, he added.

The incident took place while some soldiers on the vehicle were on routine patrol, he further said.

He also blamed the enemies of peace, a term used against Taliban fighters for organizing the attack but the outfit has yet to make comment.