A bomb blast rocked a passenger bus in the southern Russian city of Volgograd today, and officials say a female suicide bomber was behind the attack, which killed six people and injured about 30.

The suspected bomber, 30-year-old Naida Asiyalova, was from the North Caucasus, a region in southern Russia where an Islamic insurgency has been simmering for more than a decade following two separatist wars in Chechnya. A local official says the suspected attacker was married to an Islamic militant.

A spokesman for Russia's main investigative agency says Asiyalova was from Dagestan, where bombings and shootings occur almost daily. Another spokesperson says she had a fatal bone illness. He says Asiyalova's husband, Dmitry Sokolov, is an ethnic Russian, whom she had encouraged to become a rebel. Sokolov, also known as Abdul Jabba, quickly gained a reputation as an expert in explosives, he says, and is now on the run.