A nighttime missile and drone attack on Ukraine killed at least four people and injured 20 others in Kyiv, city mayor Vitali Klitschko said Friday, as Russia targeted at least six regions across the country with 407 drones and 44 missiles in one of its largest co-ordinated attacks of the three-year war.

Russia says the 'massive attack' on Kyiv was in retaliation to Ukrainian strikes. It comes after the Kremlin launched a wave of drone strikes on Ukraine’s capital late on Thursday night, forcing residents to flee underground to shelter. Volodymyr Zelenskyy reported that the assault was comprised of more than 400 drones and 40 missiles.