Islamabad, May 25 (IANS): At least 15 children were killed Saturday when the gas cylinder in their school van blew up in Pakistan's Punjab province, a media report said.

The massive explosion took place at about 7.40 a.m. when the school van was heading towards a private school in Gujrat city after collecting students from four villages.

There were an estimated 25 people on board and the students were aged between 8 and 12.

The huge blast killed 13 boys and two girls, reported Xinhua citing Dunya.

The blast also killed a teacher.

Nine people, including eight children, and a driver were reportedly injured in the blast.

Sources at Aziz Bhatti Shaheed Hospital said many of the injured had suffered burns and at least five kids were critically wounded.

The toll may rise.

The blast caused a huge fire after completely destroying the vehicle.

Initial investigation showed the blast was an accident caused by the gas cylinder of the van, said police.

Many vehicles in Pakistan are powered by compressed natural gas due to its cheap price. Due to poor manufacturing quality of gas cylinders, gas cylinder blasts frequently occur in the country.