At least 27 people were killed and dozens injured overnight in Kyiv, local authorities said, in what the city’s mayor, Vitali Klitschko, called the worst Russian attack on the capital during more than four years of air assault on Ukraine.

Russia used nearly 500 drones and more than 70 missiles in the hours-long attack on Kyiv and other parts of the country in the early hours of Thursday. Loud explosions shook the capital for several hours as waves of drones as well as cruise and ballistic missiles came towards it and Ukraine’s air defence attempted to shoot them down.

As dawn broke, fires were burning at sites across Kyiv, with strikes or debris hitting residential buildings in several districts and a hotel on one of the central boulevards. In one location on the left bank of the Dnipro River, a large section of a nine-story apartment block was ripped open and reduced to a mound of rubble. Throughout the day, rescuers picked through the remains of the block hoping to find survivors.

The death toll steadily rose during the day, and may yet climb higher, with about 70 people admitted to hospital and rescuers still searching in the ruins.

Russia regularly launches combined missile and drone attacks on the Ukrainian capital and there had been speculation for some days that another massive attack was coming. Volodymyr Zelenskyy warned Ukrainians on Wednesday that it could happen that night. “I am asking all our people to be extra careful, take care of yourselves and your children, and use shelters, this is very important,” the president said, speaking on a visit to Dublin.

City authorities said more than 50,000 people took shelter in metro stations across the capital overnight, after the warnings. Some of them brought mattresses and tents to get a few hours of sleep below ground, and at some stations there was no space to be had on the platforms as hundreds of people stretched out for the night.

“By now we are pretty used to noisy nights, but they are getting worse and worse, and today was the first time in all these years of war that I decided maybe it would be safer not to spend the night at home,” said Oleksandra Voloshyna, a medical student who slept in one of the central metro stations.

Zelenskyy, who returned early from his trip to Ireland to visit the site of one of the attacks in Kyiv on Thursday afternoon, said that if allies had followed through on agreements to provide Ukraine with air defence missiles, the damage would not have been so great. “We are fighting alone. The victims are only Ukrainians. All we ask from our partners is that they do what they agreed to,” he said.

Many Kyiv residents are paying renewed attention to strikes after more than four years of full-scale war, owing to the severity of recent mass attacks. In late May, Russia warned foreign diplomats to leave the city, saying it planned to intensify strikes on “decision-making centres” there.

During Thursday’s attack, Ukraine’s neighbour Poland, a Nato and EU member, scrambled fighter jets as a preventive measure. Finland had briefly issued a temporary aviation restriction zone in the eastern Gulf of Finland, its defence forces said on X.

In recent weeks, Ukraine has intensified its campaign of long-range drone strikes against oil refineries in Russia, causing fuel shortages across the country. Multiple Russian regions have been forced to introduce petrol rationing, while in occupied Crimea, Russian authorities have declared a state of emergency.

Ukrainian officials said they intended to keep up the pressure on Crimea, which Russia annexed in 2014 and which has served as a logistical hub for the Russian occupation of parts of south-eastern Ukraine since 2022. On Thursday morning, the governor of Russia’s Nizhny Novgorod region said one person had been killed in a drone strike on industrial facilities there.

The Russian defence ministry said it had used weapons launched from air, land and sea during Thursday’s attacks on Ukraine, and claimed it was in retaliation for Ukrainian strikes. Moscow said it had targeted military facilities and energy infrastructure in the attacks, which also hit several regions outside the capital.

The Ukrainian foreign minister, Andrii Sybiha, who is on a working visit to Japan, said on Thursday morning that it was “immoral” to claim the strikes were retaliation for Ukraine’s attacks on Russia.

Sybiha wrote on X: “In this war there is an aggressor and a country defending itself. Russia has no right to make any strikes against Ukraine, while Ukraine has every right to respond, defend from aggressor, and strike any legitimate military targets in Russia. Do not equate an aggressor and a country defending from aggression.”

He reiterated Kyiv’s urgent plea for Ukraine’s allies to supply more air defences, saying that the capital had “suffered a night of horror”.

The UK prime minister, Keir Starmer, said the attacks were “a stark reminder that while Ukraine continues to pursue peace, Putin continues to inflict suffering and violence on the Ukrainian people”.

A US-backed peace process has stalled in recent months, as Putin has shown little interest in abandoning his maximalist goals in Ukraine and the White House turned its attention to events in the Middle East instead.

On Thursday, Zelenskyy said his national security council secretary, Rustem Umerov, had been in touch with the US negotiator Jared Kushner in recent days to discuss restarting the peace process. Zelenskyy also said he hoped to meet with the US president, Donald Trump, on the sidelines of the Nato summit in Ankara next week.

As a result of the attacks, Friday has been declared a day of mourning in Kyiv, Klitschko announced.