NEW : Source : An Ilyushin-76 military transport plane is shot down near Luhansk . 3 separatists have been detained in Luhansk , says Interior Ministry official . City 's residents are no longer blocking Russian security forces , official says . 3 Ukrainian tanks cross border , go to Donetsk It was not immediately clear how many of those aboard died or survived . , he says ; Donetsk denies this claim to BBC .
NEW : Source : An Ilyushin-76 military transport plane is shot down near Luhansk . 3 separatists have been detained in Luhansk , says Interior Ministry official . City 's residents are no longer blocking Russian security forces , official says . 3 Ukrainian tanks cross border , go to Donetsk , he says ; Donetsk denies this claim to BBC .