A Suicide Bomber attacks russian Buss.

A female suicide bomber attacked a bus in southern Russia on Monday, authorities said, killing at least six people in the deadliest such blast outside the volatile North Caucasus region in nearly three years.

The bombing in Volgograd was likely to raise fears of further attacks by Islamist militants as Russia prepares to host the 2014 Winter Olympics in February in the Black Sea resort city of Sochi, not far from the mainly Muslim North Caucasus.