Source : According to Avakov , the tanks crossed the border at a checkpoint controlled by separatists in the Luhansk region of eastern Ukraine . Source : An Ilyushin-76 military transport plane is shot down near Luhansk . More than 100 separatists have been detained in Mariupol , says Interior Ministry official . city 's residents are no longer fighting Ukrainian security forces , official says . 3 Russian tanks cross border , go to Ukraine , he says ; Russia denies this statement to BBC .
Source : Source : An Ilyushin-76 military transport plane is shot down near Luhansk . More than 100 separatists have been detained in Mariupol , says Interior Ministry official . city 's residents are no longer fighting Ukrainian security forces , official says . 3 Russian tanks cross border , go to Ukraine , he says ; Russia denies this statement to BBC .