Russia launched waves of missiles and drones on Kyiv before dawn, killing 16 people including two children, and wounding well over 100 others, officials in the Ukrainian capital said.
President Volodymyr Zelensky, speaking earlier in his nightly video address, put the death toll at 14 and said rescue operations were continuing into the evening.
The Interior Ministry said more than 1,200 police and rescuers were tackling the aftermath.
Ukraine's national rescue service said the toll rose to 16 after another body had been retrieved from underneath rubble.
Mr Zelensky said dozens remained in hospital.
The rescue service said 16 of the injured were children, the largest number of children hurt in a single attack on the city since Russia started its full-scale invasion almost 3-1/2 years ago.
In an earlier post on Telegram, the president said Russia had launched more than 300 drones and eight missiles.
"Today the world has once again seen Russia's response to our desire for peace ... Therefore, peace without strength is impossible."
City authorities announced a day of mourning to be held tomorrow.
Russia's Defence Ministry said it targeted and hit Ukrainian military airfields and ammunition depots as well as businesses linked to what it called Kyiv's military-industrial complex.
Explosions rocked Kyiv from about midnight onward and blazes lit up the night sky.
Yurii Kravchuk, 62, stood wrapped in a blanket next to a damaged building with a bandage around his head.
He had heard the missile alert but did not get to a shelter in time.
"I started waking up my wife and then there was an explosion. My daughter ended up in the hospital," he said.
Russia, which denies targeting civilians, has stepped up air strikes in recent months on Ukrainian towns and cities far from the front lines of the war.
Thousands of civilians, the vast majority of them Ukrainian, have been killed since Moscow invaded in 2022.
Ukraine and Russia have held three rounds of talks in Istanbul this year that yielded exchanges of prisoners and bodies, but no breakthrough to defuse the conflict.
At one location in Kyiv, rescuers spent more than three hours reaching a man trapped in rubble by cutting through the wall of a neighbouring apartment, the Interior Ministry said.
The man talked to the emergency services during the operation and was pulled out alive, it added.
A five-month-old baby was among the wounded, with five children hospitalized, the head of Kyiv's military administration, Tymur Tkachenko, said on national television.
Schools and hospitals were among the buildings damaged across 27 locations in the capital, officials said.
"The attack was extremely insidious and deliberately calculated to overload the air defence system," Mr Zelensky wrote on X.
He posted a video of burning ruins, saying people were still trapped under the rubble of one partially-ruined residential building as of the morning.
As of now, as a result of Russia's terror attack on Kyiv, 16 people have been killed, including 2 children and one policeman. Over 150 have been injured, including 16 children and 6 policemen.
— Volodymyr Zelenskyy / Володимир Зеленський (@ZelenskyyUa) July 31, 2025
Unimaginable scale of terror and brutality.
Rescue and recovery operations are still… https://t.co/KipaDXMK2n
US President Donald Trump, speaking to reporters in the Oval Office, sharply criticized Russia's "disgusting" behavior against Ukraine and said he planned to impose sanctions on Moscow if no agreement could be reached.
Mr Trump said he was not sure whether sanctions would deter Russia.
He has given Russian President Vladimir Putin until August 8 to make a deal or else he will respond with economic pressure.
Mr Trump said US special envoy Steve Witkoff would travel to Russia after his current trip to Israel.
Ukraine votes to restore power of anti-corruption bodies
The Russian attacks come as Ukraine's parliament approved a bill restoring the independence of the country's two main anti-corruption agencies, moving to defuse a crisis that has shaken faith in President Volodymyr Zelensky's leadership.
Thousands of protesters rallied in Kyiv and other cities in recent days in a rare show of discontent after politicians led by his ruling party rushed through amendments last week to remove the body's powers.
Mr Zelensky changed course after the outcry and under pressure from European officials, who warned the move was jeopardising Ukraine's bid for European Union membership.
Politicians voted 331 to 0 in favour of the new bill, submitted by the president, that reverses measures that had given his hand-picked general prosecutor the power to transfer cases away from the agencies and reassign prosecutors.
Critics alleged the step had been designed to protect Mr Zelensky's political allies from prosecution.
Eradicating corruption and shoring up the rule of law are key requirements for Ukraine to join the EU - a move the country sees as critical to its future as it continues to fight a Russian invasion.
Demonstrations continued after the president submitted the new bill, with hundreds rallying near his office in Kyiv last night shouting: "Shame!" and "The people are the power!".
Activists also rallied near parliament ahead of today's vote to pressure politicians and burst into applause after the bill was passed.
Opposition member Yaroslav Yurchyshyn thanked Ukrainians for stopping authorities "one step from the abyss" of autocracy.
Some politicians appeared in parliament with hand-made placards mimicking those carried by protesters.
The bill now goes to President Zelensky for signature.
The National Anti-Corruption Bureau of Ukraine (NABU) and the Specialised Anti-Corruption Prosecutor's Office (SAPO) have stepped up their campaign against corruption since Russia's invasion in February 2022.
They have brought charges against politicians and senior government officials, including a former deputy prime minister who was accused last month of taking a substantial kickback.
Last week, NABU Director Semen Kryvonos said that he expected continued pressure on his agency from corrupt forces uninterested in cleaning up Ukraine.
He said he and other anti-corruption officials felt a greater sense of responsibility following the protests, but called on the country's leadership to help their effort.
"This responsibility must be shared with the government, which needs to react and say - okay, there's corruption here - let's destroy it."
