Russian weapons pounding Ukraine’s second largest city Kharkiv have killed at least three people, authorities say, while rescuers pulled survivors from the rubble of an earlier strike on an apartment block that killed 19 people in another city.

Russia’s artillery, multiple rocket launchers and tanks also injured 31 people including two children in Kharkiv, the regional governor said.

The Ukrainian president’s office said residential areas had been hit.

In the city of Chasiv Yar, further south, rescuers made voice contact with two people in the wreckage of the five-storey apartment building hit by a rocket on Saturday, and emergency services released video of workers pulling a man from under the concrete debris, where up to two dozen people were trapped.

The attack on Chasiv Yar was part of Russia’s push to capture all of the industrial Donbas region in the east, after declaring victory in Luhansk province earlier this month.

Kharkiv, in the north-east close to the Russian border but outside the Donbas, suffered heavy bombardment in the first few months of the war followed by a period of relative calm that has been shattered by renewed shelling in recent weeks.

The city’s mayor, Ihor Terekhov, said civilian infrastructure had been hit by the latest strikes, including a commercial property and a tyre repair shop.

Moscow denies targeting civilians, but many Ukrainian cities, towns and villages have been left in ruins by Russian shelling since the February 24 invasion, with basements and bomb shelters the only safe place for those who remain.

Ukrainian President Volodymyr Zelensky said Russia had carried out 34 air strikes since Saturday, while his chief of staff, Andriy Yermak, said Moscow should be designated as a state sponsor of terrorism for the apartment bombing.

Dazed residents in Chasiv Yar who survived the attack retrieved personal belongings and told stories of their escape.

“We ran to the basement, there were three hits, the first somewhere in the kitchen,” said a resident who gave her name as Ludmila.

“There was lightning. We ran towards the second entrance and then straight into the basement. We sat there all night.”

After taking Luhansk, Russian forces are now concentrating on seizing control of neighbouring Donetsk province.

Ukraine’s general staff said on Monday that Russia had launched a wave of bombardments as they seek to take Donetsk, the other province in Donbas, which has been partly controlled by Russian-backed separatists since 2014.

It said the widespread shelling amounted to preparations for an intensification of hostilities.

The US-based Institute for the Study of War said Russian troops were regrouping and that the heavy artillery fire was intended to set conditions for future ground advances by identifying Ukrainian weaknesses.

Russia’s defence ministry said its missiles struck ammunition depots in Ukraine’s central Dnipro region used to supply rocket launchers and artillery weapons.

Ukraine is preparing a counter-attack in the south of the country where Russia seized territory early in the war.

Deputy Prime Minister Iryna Vereshchuk warned civilians in the Russian-occupied Kherson region in the south on Sunday to urgently evacuate ahead of the offensive. She gave no time frame for action.

“I know for sure that there should not be women and children there, and that they should not become human shields,” she said on national television.

Ukrainian forces recaptured the village of Ivanivka in the Kherson region, a Ukrainian infantry brigade said on Monday.