"I covered my head with my hands and waited for the moment of explosion. I felt the blast wave moving down my body, everything was falling down. It felt hot at the top, this wave, the temperature, that was it. The shock and and panic come afterwards. When we got up there was smoke, everything in front of our eyes was like milk, light and white. It was very difficult to breathe because of all the glass, concrete flying around."

The 22-year-old escaped unharmed but her boyfriend was injured, and a postman doing his rounds outside was killed.

As Russia's air campaign on Ukraine intensifies, no major city is more exposed or has been hit harder than Kharkiv.

Just 18 miles from the Russian border, a missile can reach the city in under a minute.

Western military support has dried up in recent months.

A vital U.S. military aid package has been stuck in Congress amid Republican resistance, leaving Kharkiv dangerously unprotected as Governor Oleh Syniehubov explains.

"We have a catastrophic shortage of air defence systems. Not only in the Kharkiv region, but throughout the entire country. Especially in the Kharkiv region."

Ukrainian President Volodymyr Zelenskiy continues his appeal for more air defense supplies and this week said almost a quarter of Kharkiv has been destroyed.

He's accused Russia of reducing the city to rubble to clear the way for troops to advance.

With Russia intensifying aerial assaults on Ukraine's power network in recent weeks, Kharkiv has suffered rolling blackouts lasting up to 12 hours a day.

Military analyst Oleksandr Kovalenko told Reuters it's a possible tactic to scare residents out of the city.

"For the moment, Russia does not have the forces and equipment to seize the city, but they can in the medium term, they can terrorize the civilian population laying the ground for corresponding conditions."

Russia denies targeting civilians and says Ukraine's energy system is a legitimate military target.

The Russian defense ministry did not immediately respond to a request for comment for this story.

But 15 Kharkiv civilians Reuters interviewed - including Kateryna - said they are determined to stay in their homes despite the attacks.

Officials say there are no signs people are abandoning the city.