Ukrainian firefighters at work Friday in a Kyiv apartment building hit by an attack drone during a massive overnight raid that killed four people, three of them emergency workers. Photo by Sergey Dolzhenko/EPA-EFE

June 6 (UPI) -- At least four people were killed and 53 injured in Ukraine after Russia launched almost 500 drones and ballistic missiles as the country came under sustained airborne assault for the second night in a row.

Kyiv Mayor Vitali Klitschko said four people were killed and 20 injured after civilian and industrial infrastructure was targeted in six districts of the capital, but that search and rescue operations at multiple sites were continuing Friday morning, he wrote in a social media update.

Interior Minister Ihor Klymenko said in a Telegram post that three of the fatalities were emergency service staff killed as they worked under fire while the attack on Kyiv was ongoing, and that nine other State Emergency Service workers had been injured, some of them seriously.

Kyiv City Military Administration said the combined missile and drone attack caused widespread damage, both from direct hits and debris from downed drones, with subway tracks and trains sustaining damage and a residential tower block and an educational institution set ablaze.