Male suicide bomber believed behind Russian trolleybus blast

MOSCOW (Reuters) - Russian investigators said they believe a male suicide bomber carried out an attack that killed at least 14 people on a trolleybus in the southern city of Volgograd on Monday. "It is now possible to preliminarily say that the explosive device was set off by a suicide bomber - a man whose body fragments have been collected and sent for genetic testing," the federal Investigative Committee said in a statement. (Reporting by Lidia Kelly and Alissa de Carbonnel; Writing by Steve Gutterman)