The city of Kharkiv, Ukraine's second-largest, has witnessed repeated airstrikes from Russian forces.

A woman reads a book as residents find shelter from shelling in a metro station, amid Russia's attack on Ukraine, in Kharkiv, Ukraine, April 11, 2022.

A woman helps an elderly person walk down the stairs as they shelter in a metro station in northern Kharkiv from shelling in their neighborhood as Russia's attack on Ukraine continues, Ukraine, March 24, 2022.

A woman rests as residents find shelter from shelling in a metro station, amid Russia's attack on Ukraine, in Kharkiv, Ukraine, April 11, 2022.

Programming students Vladislav and Vitali Mamin study in their bomb shelter where they have been hiding with their parents since the beginning of the war in a neighborhood that has been largely abandoned and left without water, gas and heating, as Russia's attack on Ukraine continues, in Kharkiv, Ukraine, March 28, 2022.

A young man eats inside a subway car, as residents find shelter from shelling in a metro station, amid Russia's attack on Ukraine, in Kharkiv, Ukraine, April 11, 2022.

Katarina Bovt holds her son Nikita in a metro station in northern Kharkiv where they live to shelter from shelling in their neighborhood as Russia's attack on Ukraine continues, Ukraine, March 24, 2022. Bovt moved to the underground shelter three weeks ago.

A woman and her dog are seen inside a metro station used as a shelter from shelling, amid Russia's attack on Ukraine, in Kharkiv, Ukraine, April 11, 2022.

Lyubov Mikhailovna sits in her bomb shelter where she has been hiding since the beginning of the war in a neighborhood that has been largely abandoned and left without water, gas and heating, as Russia's attack on Ukraine continues, in Kharkiv, Ukraine, March 28, 2022.

A bird is seen next to a missile from a previous Russian military attack as the damaged Kharkiv Regional State Administration building seen in the background, amid Russia's attack on Ukraine, in Kharkiv, Ukraine, April 11, 2022.

Women are seen in their bomb shelter where they have been hiding since the beginning of the war in a neighborhood that has been largely abandoned and left without water, gas and heating, as Russia's attack on Ukraine continues, in Kharkiv, Ukraine, March 28, 2022.

People who are sheltering in a metro station in northern Kharkiv receive food from volunteers as Russia's attack on Ukraine continues, Ukraine, March 24, 2022.

Igor Ostrovsky opens the door to his bomb shelter where he has been hiding since the beginning of the war in a neighborhood that has been largely abandoned and left without water, gas and heating, as Russia's attack on Ukraine continues, in Kharkiv, Ukraine, March 28, 2022.

Veronika Shaposhnik, 7, sits in a stationary subway car in a metro station in northern Kharkiv where she lives with her mother to shelter from shelling in her neighborhood as Russia's attack on Ukraine continues, Ukraine, March 24, 2022.

A woman and her daughter, who have been in hiding from the bombardment since the beginning of the war, sit in the basement of an apartment building that serves as their bomb shelter in a neighborhood left without water, gas and heating after intense shelling, as Russia's attack on Ukraine continues, in Kharkiv, Ukraine, March 28, 2022.

Women sit in their bomb shelter where they have been hiding since the beginning of the war in a neighborhood that has been largely abandoned and left without water, gas and heating, as Russia's attack on Ukraine continues, in Kharkiv, Ukraine, March 28, 2022.

People shelter in a metro station in northern Kharkiv from shelling in their neighborhood as Russia's attack on Ukraine continues, Ukraine, March 24, 2022.

A man reads among the inhabitants protecting themselves from shellings in the basement of a multistory building during the Russian invasion of Ukraine on April 10, 2022, in the second-largest Ukrainian city of Kharkiv.

Alex Emelyanov, 24, speaks on the phone as residents find shelter from shelling in a metro station, amid Russia's attack on Ukraine, in Kharkiv, Ukraine, April 11, 2022.

People settle in a basement of an apartment building in Kharkiv, Ukraine, April 10, 2022.

Residents find shelter from shelling in a metro station, as Russia's attack on Ukraine continues, in Kharkiv, Ukraine, April 11, 2022.

A woman lies in a basement of an apartment building in Kharkiv, Ukraine, April 10, 2022.

Igor Ostrovsky sits in his bomb shelter where he has been hiding since the beginning of the war in a neighborhood that has been largely abandoned and left without water, gas and heating, as Russia's attack on Ukraine continues, in Kharkiv, Ukraine, March 28, 2022.

An elderly man holds a baby in the basement of a building being used as a bomb shelter during shelling in Kharkiv, Ukraine, April 10, 2022.

People sit in a stationary subway car in a metro station in northern Kharkiv where they live to shelter from shelling in their neighborhood, as Russia's attack on Ukraine continues, Ukraine, March 24, 2022.

Raisa sits in a stationary subway car in a metro station in northern Kharkiv where she lives to shelter from shelling in her neighborhood as Russia's attack on Ukraine continues, Ukraine, March 24, 2022.

A woman reads in a metro station in northern Kharkiv where she lives to shelter from shelling in her neighborhood as Russia's attack on Ukraine continues, Ukraine, March 24, 2022.

People shelter in a metro station in northern Kharkiv to escape shelling in their neighborhood as Russia's attack on Ukraine continues, Ukraine, March 24, 2022.

Lyudmila Lazareva and her dog Rika sit in a metro station in northern Kharkiv with Katarina Bovt, Kolya and their son Nikita, where they are sheltering from shelling in their neighborhood, as Russia's attack on Ukraine continues, Ukraine, March 24, 2022. Lazareva moved to the underground shelter 30 days ago after the apartment building next to hers got hit by a shell on the first day of the war, and she only leaves the station to briefly walk her dog.