A suicidal attack in the city of Samarra\', north of Baghdad, killed four people on Sunday, less than a day when a car bomb attack killed and injured scores of people in the same city. Two suicide attackers blew themselves up at a checkpoint in central Samarra, a police source told KUNA. The explosion killed four people and wounded 15 others, he added. A booby-trapped car exploded in Samarra last night killing and injuring scores of people.