A <a href="https://en.wikipedia.org/wiki/Gas_cylinder" id="mwAZI" rel="mw:WikiLink" title="Gas cylinder">gas cylinder</a> <a href="https://en.wikipedia.org/wiki/2013_Pakistan_gas_bus_explosion" id="mwAZM" rel="mw:WikiLink" title="2013 Pakistan gas bus explosion">explodes</a> on a school bus in the Pakistani city of <a class="mw-redirect" href="https://en.wikipedia.org/wiki/Gujrat_City" id="mwAZQ" rel="mw:WikiLink" title="Gujrat City">Gujrat</a>, killing at least 18 people.