so-called crimean authorities. >> for the second day in a row, a team of european oh observers was turned away from the crimean border, because there were gun-toting masked men wearing russian-type clothing. russia is claiming that was a convoy that failed to obtain something called an official invitation. and that meant some tense moments at a checkpoint and our matthew chance was there. >> reporter: we're here at this checkpoint near the crimean peninsula. i can tell you, the monitors there from the osca, the organization for security and cooperation in europe, they have just been turned back again from this checkpoint after trying to negotiate with those pro-russian gunmen over there, stopping this mission of the oac from entering crimea. trying to negotiate with them to let them through, at least a portion of them through. that's not been permitted. and, of course, that's caused a great deal of anger amongst the crowds that have gathered here. many of them ethnic tartar, some