The attack used almost 500 drones and missiles, breaking a record set just days earlier, as Russia tries to overwhelm Ukraine’s air defenses, which shot down most of the weapons.

The warring sides also exchanged prisoners in one of the few results of talks last week, and Russia reported new attacks on the front line.

A concentrated, nine-minute-long Russian drone attack on Ukraine's second-largest city killed six people and injured 64, Ukrainian officials said.