Ukrainian police have opened three criminal cases into the incident at the Ukrainian part of the border with Russia, where an unidentified man blew himself up and seriously wounded two border guards early Friday. The cases were launched in connection with attempted murder, smuggling and illegal movement across the border, the press service of Ukrainian police in Sumy region said. The incident occurred shortly after midnight at the Bachevsk checkpoint in Ukraine\'s northern Sumy region, when a man detonated an explosive device attached to his body while being interviewed by the Ukrainian border guards. The man, who was one of the five passengers of a minibus with Moldovan number plate, showed a false Russian passport when the border guards stop the vehicle. During an additional check in the passport control booth, the man refused to give his real documents and blew up himself. The identity of the man and his motive for suicide were not immediately clear. According to the local media, the man had Russian citizenship and lived in Chechnya republic. A joint investigation team grouping the state prosecutors\' office, the Interior Ministry, the country\'s security service and border service were at the scene. The Bachevsk checkpoint has resumed operation Friday morning after temporary suspension through the night.