By Marton Dunai BICSKE, Hungary (Reuters) - Hungarian police halted a train packed with migrants bound for the Austrian border and tried to force them to disembark in a town with a detention camp on Thursday, a confrontation that has become a focus of Europe's migration crisis. After shutting migrants out of the main train station in the capital Budapest for two days, authorities allowed exhausted and confused migrants to board a westbound train. Fearing detention, some migrants banged on windows chanting "No camp! No camp!" One group pushed back dozens of riot police guarding a stairwell to fight their way back on board.