An explosion rocked an Internet cafe in the Afghan capital Saturday, killing two Afghans, police said. Officials were investigating whether the blast was caused by a suicide attacker. Five people were injured in the explosion at the Park Net Cafe in Kabul's upscale Shahr-e-Naw district, a hangout also popular with foreigners, said city police chief Gen. Akram Khakrezwal, adding that all the victims were Afghans. "It was an explosion, but we still don't know if it was a suicide attack," Khakrezwal said, declining to elaborate. Nick Downie, head of the Afghan NGO Security Organization, which advises relief groups and sent representatives to the scene, said bloody chest injuries to one dead man suggested a suicide attack. Khakrezwal said police had detained a guard, the owner of the cafe and another manager for questioning.