Seventeen Pakistani children burnt to death on Saturday when a gas cylinder on the bus taking them to school exploded, media said.
Ten children were injured in the blaze on the outskirts of Gujrat, 100 miles (170 km) southeast of Islamabad, DawnNews said.
Many vehicles in energy-starved Pakistan are powered by relatively cheap compressed natural gas and cylinder blasts are common.
More top news
Figures suggest that more than 11 million homes, or 42%, are in credit to their energy company.
Undivided, which represents more than 4 million young people, has set out its top issues in an open letter to political leaders.
John Wombell, 58, was jailed for eight weeks after admitting making the grossly offensive call to the Broxtowe MP's office last November.