Miriam Elder reports at GlobalPost on the explosion in Stavropol, which took place next to a centrally-located concert hall shortly before a Chechen folk dance troupe was to perform there. LJ user dimazelensky, whose office is inside the concert hall building, wrote (RUS) that the police had cordoned it off some 40 minutes before the blast. Twitter updates (RUS, ENG) are here: #stavropol; a Stavropol city forum discussion (RUS) is here.