A bomb blast has hit a school bus in the north-western Pakistani city of Peshawar, killing the driver and a 13-year-old boy.
The roadside bomb, of the type used against Nato troops in Afghanistan, was planted in a bin.
The device went off in the busy Bhana Marri area on the Kohut road, the scene of many blasts.
Last week a suicide bomb claimed by the Taliban killed more than 40 people in north-west Pakistan.
A 13-year-old girl is among four people seriously injured after Monday's explosion, police say.
Six-year-old Eman, one of the wounded, told Reuters TV from her hospital bed: "When I saw the smoke, I ran towards my teachers at the back [of the bus]. The teachers said 'come, come'. So we got off the bus."
Peshawar is close to Pakistan's insurgency heartland tribal regions and the Afghan border.
The city has been the scene of frequent attacks by the Taliban, including on government installations and security force targets.
Correspondents say that militants in the north-west have frequently attacked schools - especially girls' schools - but usually when children are not there.
Police officials said the bomb may have been intended for police patrols that frequently pass by the area.
Police are also examining the possibility that the bomb may have missed its intended target.
The bus was hit near a private school, police say, and the blast ripped through the vehicle, leaving charred wreckage and a crater on the ground nearby.
Words painted in English which read "Islamia Model High School" were still visible on the vehicle's side.