Russia bombed a blood transfusion centre in the latest of a string of attacks across Ukraine which killed at least six people, while Kyiv hit bridges in occupied territories on Sunday.
A "guided air bomb" hit the medical complex in Kupiansk, a railway hub in the Kharkiv region, fewer than 10 miles from the front on Saturday night, said President Volodymyr Zelenskyy, calling the attack a "war crime".
An unconfirmed number of casualties were reported, he added, in an area recently liberated by Ukrainian troops.
"Dead and wounded are reported," Mr Zelenskyy wrote on social media.
"Rescuers are extinguishing the fire. This war crime alone says everything about Russian aggression.
“Defeating terrorists is a matter of honour for everyone who values life.”
Ukraine's air defence destroyed 30 of 40 cruise missiles and all 27 of the Shahed drones that Russia launched overnight, the Air Force said on the Telegram messaging channel on Sunday.
It said has Russia also launched three Kinzhal hypersonic missiles but did not disclose any further information on them.
Russia has yet to comment on the incident but denies targeting civilians in Ukraine.
Its air defences were also at work on Sunday, as Ukraine targeted two bridges on occupied territory.
"The enemy launched a missile attack near the Chongar bridge" that connects southern Ukraine to the annexed Crimean peninsula, Moscow-installed governor Sergei Aksyonov said on Telegram.
"One hit, some missiles were shot down," Mr Aksyonov said, adding that repair work was ongoing.
A separate attack on a bridge near Genichesk in southern Kherson wounded a civilian and damaged a gas pipeline, cutting supplies for about 20,000 residents, Moscow-installed official Vladimir Saldo said.
Russian air defence also shot down a drone approaching the Russian capital, which until recent months was almost never targeted.
And at Vnukovo Airport, which is 15km south-west of Moscow, flights were suspended briefly on Sunday morning after a drone was shot down in the airspace around the city.
The drone was destroyed by air defence systems in the Podolsk region of suburban Moscow, the Russian Defence Ministry said.
Ukrainian authorities, who generally avoid commenting on attacks on Russian soil, did not say who was behind the raid.
The strike on the blood transfusion centre came shortly after Mr Zelenskyy said Russian missiles had hit a building housing the Ukrainian aeronautics group Motor Sich, a maker of plane and helicopter engines and other components.
It is one of several companies requisitioned by the government since Moscow's invasion. The Motor Sich site is near Khmelnytskyi in western Ukraine, about 300km south-west of Kyiv.
The region, home to a major Ukrainian airbase, has been hit regularly by Russian air strikes.
In his evening address, Mr Zelenskyy remained defiant, insisting "no matter how many such Russian attacks there are, they will still do nothing for the enemy".
On Saturday Ukraine claimed it "blew up" the Russian tanker SIG that was transporting fuel for troops.
The SIG is under US sanctions for supplying jet fuel to Russian forces in Syria, allied with President Bashar Al Assad.
Russia condemned Ukraine for the attack, on what it said was a civilian vessel.
“There can be no justification for such barbaric actions, they will not go unanswered and their authors and perpetrators will inevitably be punished,” Foreign Ministry spokeswoman Maria Zakharova wrote on the Telegram messaging app.
It was the second sea attack in a day, with Kyiv also striking the major port city of Novorossiysk – the first time a commercial Russian port has been hit in the war.
The drone strike halted maritime traffic briefly.
The ship was holed at the waterline in the area of the engine room but was still afloat, the Russian agency said.
The overnight attacks came as Saudi Arabia is hosting peace talks in Jeddah aimed at ending the 18-month-old conflict, bringing together 40 countries, including China, India and South Africa, but excluding Russia.
Kyiv has remained optimistic on the talks, which Mr Zelenskyy hopes will lead to a peace summit later in the year.
“I expect that the conversation will be difficult but behind us is truth, behind us – goodness,” Andriy Yermak, head of the presidential office and a leading envoy for the talks, said.
The talks concluded on Saturday and no final declaration was released.
But a European source said there had been agreement that respect for Ukraine's "territorial integrity and sovereignty" should be "at the heart of any peace settlement".
On Sunday, Moscow said the talks were a "doomed Western attempt" to align the Global South behind Kyiv.
Russian Deputy Foreign Minister Sergei Ryabkov was quoted by the state news agency Tass calling the meeting "a reflection of the West's attempt to continue futile, doomed efforts to mobilise the international community, and more precisely, the Global South, even if not entirely, in support of the so-called Zelenskyy formula, which is doomed and untenable from the outset".