Russian drones and missiles pounded Ukrainian cities such as Kyiv and Dnipro early on ​Tuesday, killing at least 10 people and wounding about 100, authorities said, following days of warnings about Moscow’s plans for a ‌major assault.

Russia has targeted Ukraine’s power supply and infrastructure in a war now more than four years old, while Ukraine has stepped up attacks this year on Russian oil facilities. Both deny targeting civilians.

Last week, the Kremlin warned that it intended “systematic strikes” on targets in Kyiv in response to a drone attack on a dormitory in Ukraine’s Russian-held region of ​Luhansk, which killed 21. Ukraine denied the attack.

Photographs showed large explosions and plumes of smoke billowing over high-rise buildings in Kyiv, where ​overnight strikes killed four people and wounded 58, including children, according to the capital’s mayor, Vitali Klitschko.

“We couldn’t understand what ⁠was happening - some kind of apocalypse?” said Olha Mudra, speaking at the site of one strike, accompanied by her six-year-old daughter Natalia.

“Everything was covered (with debris), ​everything in smoke, you could see nothing,” she added, as she stood in front of a destroyed residential building and damaged cars.

A suspected missile strike ​on a 24-storey apartment building triggered a collapse, leaving people probably trapped under the rubble, Klitschko added, while a nine-storey apartment block was among other buildings set ablaze by suspected missile debris.

“In the Obolon district, cars are burning after being struck by falling missile debris,” Klitschko said. “There are also fires at two locations in open areas, including one near ​a kindergarten.”

Thousands seeking shelter flooded into the Kyiv subway system early on Tuesday, witnesses said, some carrying belongings and mattresses, as the sound of defence ​systems repelling Russian attacks filled the air.

Warnings of a major attack

Six people were killed and 36 ‌injured in ⁠a missile and drone attack on the southeastern city of Dnipro and its surroundings, regional governor Oleksandr Hanzha said on the Telegram messaging app.

All the injured were in hospital in moderate condition, he added, posting pictures of destroyed residential buildings, burnt-out vehicles and a damaged children’s playground.

Air raid warnings sounded over much of the country early on Tuesday after Ukrainian President Volodymyr Zelenskiy’s warnings the previous day of a possible major assault.

“Intelligence warnings regarding Russian strikes remain in effect. ​A massive strike is possible. They ​have prepared one,” Zelenskiy said in ⁠his nightly video address.

“Our defenders are ready 24/7 to the fullest extent possible with the supplies currently available.”

In Ukraine’s northeastern region of Kharkiv, a child was among the 10 people injured in drone and missile attacks, Mayor Ihor ​Terekhov said on Telegram.

Russian regions also came under attack. The Ilsky oil refinery, in the southern Russian region ​of Krasnodar, caught fire after ⁠a drone attack, local authorities said on Telegram on Tuesday.

In Russia’s Belgorod region bordering Ukraine, an 11-year-old boy was injured after a Ukrainian drone hit a home, local authorities said on Telegram.

Russia downed a total of 148 Ukrainian drones overnight, Russian news agencies said, citing the defence ministry.

Air defence systems were also repelling drone ⁠attacks over ​Sevastopol, a Russian naval fleet base, in Russia-occupied Crimea, authorities there said.

Reuters could not independently ​verify all the reports.

The Ukraine war has ground on since Russia launched its full-scale invasion in February 2022. Efforts to end it have made little progress, with the administration of US President ​Donald Trump focused on conflicts in the Middle East.