where is the bomb come from jaffna roadside.Now who have bomb in Sri Lanka‏

Two children died from a blast at jaffna today. It is identified the students died at the incident are jaffna kozhumbuththurai Hindu college. The bomb which was not burse found by the children resulted the death. Reports says while the children returning the home at found the bomb which was lying on the roadside. Sri Lanka take the responsibility without telling it's LTTE.