A major dam and hydroelectric power plant in southern Ukraine were severely damaged on Tuesday, unleashing flooding near the front lines. Ukraine and Russia each blamed the other for attacking the site, destroying the plant and damaging the dam. As water gushed from the facility on the Dnieper River, which separates Ukrainian and Russian forces, officials on both sides ordered residents to evacuate. The world’s atomic energy watchdog warned the warring sides not to undermine the safety of the nearby nuclear power plant in Zaporizhzhia but said there was currently “no immediate risk” to it.