At least 17 Pakistani school children are dead after a gas cylinder on their school bus exploded.<br/> <br />Local media say ten other children were injured. Most of the children were age 8 or younger.<br/> <br />It happened about 100 miles southeast of Islamabad.<br/> <br />A police officer said the fire started when the bus driver shifted from petrol to natural gas.<br/> <br />Many vehicles in energy-starved Pakistan are powered by relatively cheap compressed natural gas and cylinder blasts are common.
