Thousands of Kyiv residents spent the night in bomb shelters and metro stations as rocket attacks and explosions rocked the city.
Across Ukraine’s capital and other cities, air raid sirens urged citizens to take cover in shelters.
Above ground, the sound of gunfire and missile strikes continued into the early hours of Friday morning.
President Volodymyr Zelensky said Russian strikes targeted civilian and military zones.
“Last time our capital experienced anything like this was in 1941 when it was attacked by Nazi Germany,” the country’s foreign minister said.
One Kyiv resident who spoke to the BBC said she decided to take shelter in a subway station out of fear for her safety.
“Yesterday I woke up from the noise of explosions, I saw flash fires. It was scary,” Ksenia told the BBC.
She says she is trying not to think too much about the physical threat to her life.
“I feel very, very, very angry because it’s not a normal situation. It’s my country, it’s my land, it’s my city. And now all of us, all of Ukrainians are under attack. Multiple cities are under attack.”
Speaking from the metro station where she is sheltering with supplies to last her as long as necessary, Ksenia pleaded for the world to give more support to Ukraine.
“All the sanctions are good, but it’s not enough. This war is not about only Ukraine and our independence and safety. We are a shield for you – Europe and the world.”
Instead of following suggestions to go to bomb shelters, other residents decided to leave central Kyiv entirely.
Campaigner Oleksandra Matviychuk, speaking to the BBC from the outskirts of the capital, says she doesn’t know what she will find when she returns home.
“I plan to return to my home when the alarm sirens finish. If it’s [still] a home. Last night the Russians shelled a housing block. These days will be difficult for us,” she added.
Attempts by Kyiv’s 2.8 million residents to get a peaceful night’s sleep were interrupted by explosions.
Another resident – Maykl – told the BBC that he was awoken in the middle of the night by a huge explosion.
“It was a missile. Ten or 12 very large noises. Of course, people feel panic and start buying necessities. Some have decided to leave Kyiv and we have a traffic jam 30 km long.”
But having fled to the capital from Ukraine’s Donetsk region himself a few years ago, Maykl says he is an “experienced refugee” and not in a panic.
“We have boxes with all our papers. We have some clothes, food, and we’re ready to leave. But my guess is we will win, because our army is strong enough to fight.”
In the eastern Ukrainian city of Kharkiv, Ukraine’s second-largest, the mayor has urged residents to head to subway stations, bomb shelters and basements.
Olga, who lives in the city, told the BBC she spent all day in the bathroom with her children.
“We heard gunfire and explosions all the time,” she says, adding that she spent the day trying to stay in touch with friends and family on the internet.
“We are holding on. We don’t want to be in Russia. We are independent and the free state of Ukraine, and we will stand until the end.”