NEW : The bus was not speeding at the time of the crash , a Swiss prosecutor says . NEW : The impact was so great that their seat belts did not protect the children , he says . Belgian Prime Minister : The drivers had respected regulations regarding rest time , he added . Missing include two Dutch ##men , one German and one Pole . The bus was returning to Belgium from a ski trip with 52 people aboard , most of them children .
NEW : The bus was not speeding at the time of the crash , a Swiss prosecutor says . NEW : The impact was so great that their seat belts did not protect the children , he says . Belgian Prime Minister : Missing include two Dutch ##men , one German and one Pole . The bus was returning to Belgium from a ski trip with 52 people aboard , most of them children .