“We can hear the sounds right now of air strikes nearby,” Svitlana, 40, told the BBC. She was hiding in Chernihiv on Friday morning under her dining table with her two children, aged six and three, and her neighbours in her five-storey apartment building.

“There are no military targets here, there is only a cemetery, residential buildings, clinics and a hospital, why are they bombing us?” Svitlana said.

Russia escalated its air campaign against Ukraine on Thursday and Friday, killing at least 47 civilians in Chernihiv and continuing to lay siege to residential areas in Mariupol, Borodyanka and Kharkiv.

Aerial attacks in Chernihiv destroyed high-rise apartments buildings and damaged a clinic and hospital, sending residents fleeing into the streets and to underground bunkers.

An apartment building 500m from Svitlana’s was destroyed on Thursday, she said. Her building sits just 50m from a children’s hospital, where staff had taken children including cancer patients to a shelter between the two buildings but were not able to create a sterile environment there and were struggling to evacuate the children.

Images and video footage from Chernihiv, which is 90 miles (144 km) north of the capital Kyiv and home to about 300,000 people, showed indiscriminate destruction to residential areas, drawing immediate comparisons to the devastating Russian bombing campaigns against Grozny in the late 1990s and Aleppo in 2016. Chernihiv has reportedly been surrounded by Russian forces.

The BBC verified the full names and exact locations of people it spoke to in Chernihiv and other cities under attack but is not publishing those details for safety reasons.

Katya, a 22-year-old nurse in Chernihiv, said she had been able to hear the sounds of continuous shelling throughout Friday morning.

“I’m calling back now because I don’t know if it will be too late, I don’t know if we will survive,” she said.

“There is me, my mother, my grandma and our neighbour and we all are hiding in our house. At this very moment I can hear the shelling. Local hospitals and schools are destroyed. Russians promised not to kill civilians but they are killing.”

“We were hiding in the staircase near our sixth-floor apartment and we could hear planes flying overhead and they sounded low,” she said. “Suddenly there was a boom and the whole building shook. We ran outside and people were screaming. We could see that the missile went through our building and hit the next building.”

Russia and Ukraine agreed on Thursday to the need for humanitarian corridors to help civilians escape from cities under siege, but residents in Chernihiv and in the southern port city of Mariupol told the BBC on Friday that there had been no significant break in the aerial bombardment to allow people to move.

The escalating strikes on residential areas raised concerns that Russia would continue to target civilians from the air after meeting staunch resistance from Ukraine’s army and failing to make significant progress on the ground. The bombing of Chernihiv on Tuesday came after the Russian president, Vladimir Putin, told French leader Emmanuel Macron that Russia would achieve its military goals in Ukraine “whatever happens”.

Heavy bombardment continued in Mariupol, which entered its third day on Friday without power, water or its sanitation system. The city’s deputy mayor, Serhiy Orlov, told the BBC on Friday that the city council was trying to create a humanitarian corridor to allow civilians to escape.

“We have been preparing everything we can, transport, routes, supplies, but as of Friday morning there is no agreement how and when we can get people out and there has been no break in the shelling,” he said.

“What you have to understand is this is not troops fighting troops, Putin sees destruction and humanitarian crisis as the goal. He wants to terrify people and force them to lose their will.”

In Kharkiv, in the east, Ukrainian authorities said the city had been “pounded all night” by indiscriminate shelling, which UN prosecutors are investigating as a possible war crime.

“Yes the shelling has been constant,” said Elena, a 59-year-old engineer who was hiding in the basement of her apartment building with her daughter and grandchild. “We can hear planes flying overhead and explosions,” she said. “Nothing has hit our building yet.”

Masha, a 24-year-old communications manager in western Ukraine, whose aunt Larysa survived the direct strike on her Chernihiv apartment building, said she had “no feelings right now, only emptiness”.

“It is the eighth day of the war and I can’t feel anything – no fear, no nothing. Chernihiv was my second home, and now it’s destroyed,” Masha said.

“I didn’t realise what was really happening until the moment I saw a slow-motion video of a missile hitting the building I used to live in.”

Svitlana, who was sheltering in her Chernihiv apartment with her two children and neighbours, said she could only wait for a break in the shelling.

“We are terrified here but we have to be brave,” she said. “Ukraine above all.”

Orysia Khimiak contributed to this report.