Senior city administration official Siraj Ahmed said the bomb was placed in a dustbin on a roadside.

“When I saw the smoke, I ran toward my teachers at the back (of the bus). The teachers said ‘come, come’. So we got off the bus,” 6-year-old Eman, one of the wounded, said from a hospital where she was lying on a bed with her head bandaged.

The driver of the bus, who was also wounded said the bomb went off shortly after some of the teachers stepped off: “There was a sudden explosion. After that, I did not have my senses. I fell.”

Ahmed said one passerby was killed and the driver, two girl students and another passerby were wounded.

Two suspects were detained at the scene. A police official said the bomb may have been intended for one of the police patrols that frequently pass by the area.

Pakistan’s government, which Washington sees as an ally in its war against militancy, faces a growing threat from what officials and analysts call a growing nexus of militant groups.

It’s a murky mix that includes Al-Qaeda, Pakistani Taleban militants and other groups. Some are anti-Western while others are driven mostly by sectarian hatred.