Residents of the Ukrainian capital Kyiv were urged to head to air raid shelters as sirens wailed across the city early on Friday morning, a day after Russia carried out the biggest aerial assault since it started the war in February. Shortly after 2:00am (00:00 GMT), Kyiv's city government issued an alert on its Telegram messaging app calling on residents to proceed to shelters. Oleksiy Kuleba, governor of the Kyiv region, said on Telegram that an "attack by drones" was under way. A Reuters witness 20km (12 miles) south of Kyiv heard several explosions and the sound of anti-aircraft fire. Local media outlet The Kyiv Independent reported that air raid alerts were blaring in the Kyiv, Cherkasy and Kirovohrad regions due to possible Russian drone attacks.