Sergey Bubka tells CNN he wants the violence in Ukraine to stop . He says that if Russia doesn't get involved, then it will be a "catastrophe" for both sides. Two members of Ukraine Winter Olympics team withdraw from Sochi Games .
Sergey Bubka tells CNN he wants the violence in Ukraine to stop . Former Olympic champion wants government and protesters to `` start dialogue again '' CNN told at least 100 people have died and 500 injured since Thursday morning . Two members of Ukraine Winter Olympics team withdraw from Sochi Games .