Russian forces launched a major drone and missile attack on Kyiv overnight, killing 18 people, in what the city’s mayor has described as the “most massive attack” on the Ukrainian capital.

Vitaly Klitschko declared Friday a day of mourning and said around 90 people were injured. He said an ambulance station was among the places hit in the strikes.

Although previous attacks have killed more people, this latest barrage deployed the largest number of weapons on the capital and hit locations over a very wide area of Kyiv.

Several neighbourhoods were evacuated as strikes rocked buildings throughout the city, hours after Ukrainian President Volodymyr Zelensky warned Russia was preparing an attack.

Moscow said its forces hit what they called military plants in retaliation against attacks on Russian civilian infrastructure.

Kremlin spokesman Dmitry Peskov told reporters on Thursday that Russia would “continue to increase pressure on the Kyiv regime in order to achieve our set goals”.

Ukraine accused Moscow of targeting civilian areas and said it would be wrong to equate the actions of the “aggressor and a country defending itself”.

Children were among the “significant number” of casualties, Tymur Tkachenko, the head of Kyiv’s ​military administration, said.

“The enemy is once again deliberately targeting residential areas and killing civilians,” he said early on Thursday.

Among the places hit by the strikes was a high-rise apartment building with part of the building blown off in south-east Kyiv.

In a video posted on Telegram, Klitschko said rescuers were trying to find, among others, a 15-year-old girl and her family.

On the city’s left bank, in Darnitskyi district in south-east Kyiv, two missiles hit a residential area directly, causing devastation.

One missile left a giant crater next to a kindergarten and the buildings all around have been gutted by fire, their metal balconies twisted.

The second missile landed a few steps away and hit the end of a 9-storey block of flats. It has collapsed, sliding off the face of the building, into a heap of concrete. One local told the BBC that several people were missing and they may have been in the basement, sheltering.

There are smashed cars and smashed windows and a thick layer of grey ash coating everything and everyone.

Rescuers have been trying to dig through the rubble to reach them as relatives watch, in tears.

Svitlana, who lives next to the building that was hit, told the BBC she was hiding in the corridor during the air raid and heard the explosions.

“It wasn’t scary,” she shrugged, “Because I’ve been through it all before.” She then revealed that she had been badly injured in another Russian strike on another town which killed her mother. Two years later, her son was killed in action fighting for Ukraine.

Oleksiy, his face covered in cuts and blood, told the BBC he had stepped outside to smoke after he heard the first missile, then the second one landed and he was hit by flying glass.

“This is not retaliation by Russia for Ukrainian strikes,” he said, dismissing Moscow’s explanation for its latest attack. “They started this war. This is a residential area. And they targeted it.”

The attack on Kyiv lasted more than 11 hours and came in several waves starting with a drone strike on Kyiv’s historic quarter, setting off a fire in a hotel in the city centre.

At 01:00, dozens of ballistic and cruise missiles were fired. A brief lull preceded another dozen of cruise missiles at 03:00, followed by a swarm of drones which targeted the capital until dawn.

Residents of Kyiv who have lived through four-and-a-half years of war say they have perceived a change in the pattern of Russia’s assaults on the capital over the last two months. Attacks may now happen less frequently – albeit still every few days – but last longer, and seem more powerful and widespread.

Ukrainian military experts described the latest barrage as one of the most challenging assaults for the country’s air defences in recent months.

Aviation expert Bohdan Dolintsev told Ukrainian media that Russia’s technique of using multiple types of weapons within the same time window, and wearing down Ukraine’s defences creates an exceptionally complex challenge for Ukraine’s air defence systems.

Ukraine’s air force said Russia had launched 74 missiles and 496 drones overnight, mainly targeting the capital.

While the country’s air defences were able to repel most of these, 25 ballistics missiles and 12 drones struck 33 locations.

In the wake of the attacks, Ukraine urged allies to send more air defence systems. Zelensky appealed to Washington to grant Ukraine licences to manufacture Patriot defence missiles.

Russia also hit military bases in central and eastern Ukraine, according to the Ministry of Defence.

It claimed to have targeted Ukrainian defence and energy infrastructure in response to what it called “terrorist attacks launched by the Kyiv regime against civilian infrastructure” in Russia.

Kyiv has recently launched long-range attacks on Russian power stations from Moscow to the Black Sea.

The attacks led to a rare confession by Russian President Vladimir Putin that his country was facing fuel shortages.

Ukrainian Foreign Minister Andriy Sybiha said it would be “immoral” to justify the Russian strikes by saying they were a response to Kyiv’s long-range attacks on Russia. “In this war, there is an aggressor and a country defending itself,” he said.

Russia launched its full-scale invasion of Ukraine in February 2022, and currently controls approximately one-fifth of Ukrainian territory.

Additional reporting: Mariana Matveichuk