Russian air attacks killed 18 and wounded dozens in Kyiv, Dnipro, Kharkiv. Moscow claimed attacks were retaliation for a drone attack in Luhansk. Kyiv's 24-storey building collapsed from a missile strike. Dnipro: 4 killed, 16 injured; Kharkiv: 10 injured. Thousands fled to Kyiv metro as air raid warnings spread. Zelenskyy warned of ongoing Russian strike threats