Thirteen militants botched up a car bomb attack as the explosive charge they were working on blew up and killed them, a security source said Monday.The incident took place at a terror hotbed in Al-Malh district of Samarra city, northwest Baghdad, the source told KUNA.The blast kill all the 13 militants who were at the hotbed and are believed to be members of the Islamic State of Iraq and the Levant (ISIL).