KYIV, Ukraine—A Russian airstrike hit a maternity hospital in the besieged southern Ukrainian city of Mariupol, local authorities said, as Moscow’s invasion has shifted to a new, more destructive phase aimed at civilian targets.Video footage released by the Mariupol mayor’s office showed wounded people being pulled out of the partially collapsed hospital complex. A wide, deep bomb crater was visible, with signs that the blast, which took place around 5 p.m. local time Wednesday, had knocked down trees and torched cars. Nobody was killed in the blast and 17 people were wounded, officials said. Mariupol has faced more than a week of Russian shelling that has cut off water and power in the city of over 400,000, where remaining residents have been hunkering down in basements. More than 1,200 c...