A Russian strike on Kharkiv, Ukraine's second-largest city, has killed six civilians and injured 10, regional officials say.
Ukraine's national police said the attack in the early hours of Saturday was launched by drones.
It published pictures of blazes that had broken out on city streets and next to buildings.
"As of this morning, there are six dead and 10 wounded as a result of the night strike on Shevchenkivskyi district," Kharkiv Mayor Ihor Terekhov said on the Telegram messaging app.
"The attack hit residential areas - at least nine high-rise buildings, three dormitories, a number of administrative buildings, a shop, a petrol station, a service station and cars were damaged," he said.
The strike had occurred just after midnight, news reports said.
Ukraine's military said on Facebook its air defences destroyed 28 of 32 drones and three of six missiles launched by Russia.
Kharkiv, in Ukraine's northeast, has been a frequent Russian target, with attacks intensifying in recent weeks.
On Wednesday, a drone attack on the city killed four people and badly damaged apartment blocks.
President Voldodymyr Zelenskiy's chief of Staff, Andriy Yermak, told the news outlet Politico in an interview published on Thursday that he considered Kharkiv the most likely target for any new Russian offensive in May or June.
Kharkiv regional Governor Oleh Synehubov reported a strike on a residential building and a missile attack on a village north of Kharkiv city. No casualties were reported in either incident.
Air raid alerts remained in effect for Kharkiv and most of the country including the capital Kyiv for several hours after the strikes.
The strike came after Russian state-run RIA news agency quoted the press service of the Russian-controlled facility as saying military drones had attacked the Zaporizhzhia nuclear power plant but caused no damage to its critical infrastructure.
Reuters could not independently verify the alleged incident.
In the past, both sides in the two-year-old conflict have accused each other of shelling the plant, none of whose six reactors are operating.
"Recently, Ukrainian forces' combat drones have been flying in the area of the Zaporizhzhia NPP," RIA quoted the press service as saying.
"In particular, arrivals were recorded today in the area of the cargo port and nitrogen-oxygen station No. 2 of the Zaporizhzhia NPP."
There was no immediate public comment on the Russian allegations from Ukraine.
Separately an air alert was issued in the Ukraine-controlled part of Zaporizhzhia region on Friday afternoon.
Regional governor Ivan Fedorov said a Russian air attack killed two people and injured six more.
