At least six people, were killed and about 40 injured in a bomb explosion outside a concert hall in Stavropol, southern Russia. Five women and a girl of 12 were killed when it exploded in the street minutes before a Chechen dance troupe was due to perform inside the building. <br/> <br/>The ethnically Russian city lies close to the troubled North Caucasus but has largely escaped militant violence. <br/> <br/>Stavropol's governor, Valery Gayevsky, described the bombing as a brutal provocation. <br/><br/>