KYIV, Ukraine (AP) — Russia launched its biggest aerial attack against Ukraine overnight, a Ukrainian official said Sunday, part of an escalating bombing campaign that has further dashed hopes for a breakthrough in efforts to end the 3-year-old war.

Russia launched 537 drones and missiles into Ukraine overnight into Sunday morning, according to Ukraine's air force, with a Ukrainian F-16 fighter jet and its pilot also reported lost during efforts to repel the attack.

Russia launched hundreds of drones and missiles at Ukraine overnight Sunday, in what Kyiv is calling Russia’s largest aerial assault since its full-scale invasion. The attacks killed at least four civilians and targeted regions far from the frontlines,