Russia, using missiles and drones, launched one of the biggest assaults on the Ukrainian capital, Kyiv, since the beginning of the war more than three years ago and hours after a prisoner exchange began.

Russia launched 250 drones and 14 ballistic missiles against Kyiv, Ukraine's air force said, causing fires in residential buildings. It was one of the biggest combined aerial assaults on the city since the war began. The air force said it had downed six missiles and 245 drones.

Russia and Ukraine have exchanged hundreds more prisoners as part of a major swap after an overnight attack on the Ukrainian capital that injured at least 15.