A 6-year-old girl named Tanya died alone and terrified from dehydration in the besieged city of Mariupol over a week after Russia’s invading forces cut off the water and power supply, according to Ukrainian officials.

In a heartbreaking post on Telegram, Mayor Vadim Boychenko wrote that the girl’s body was discovered in the rubble of a home destroyed by Russian shelling. The girl’s mother was also found dead at the scene, according to the mayor, who said it’s not clear how long Tanya was suffering before she died.

“We cannot imagine how much suffering an innocent child had to endure,” Boychenko wrote on Tuesday. “In the last minutes of her life she was alone, exhausted, frightened, terribly thirsty. This is just one of the many stories of Mariupol, which has been surviving the blockade for eight days.”

Shortly before Boychenko’s announcement, Ukrainian President Volodymyr Zelensky said in a video address that the child’s death was “probably the first such case since the Second World War,” adding: “Listen to me carefully: In 2022, a child died from dehydration.”

The girl’s death has not been independently confirmed, but it’s just one tale of horror from Mariupol, where Russian forces have trapped hundreds of thousands of people with no running water and no power. One city official described a humanitarian disaster earlier in the week, telling The New York Times he’d seen people “drink from puddles in the streets.”

Foreign Minister Dmytro Kuleba wrote Tuesday morning: “Russia holds 300k civilians hostage in Mariupol, prevents humanitarian evacuation despite agreements with ICRC mediation. One child died of dehydration (!) yesterday! War crimes are part of Russia’s deliberate strategy. I urge all states to publicly demand: RUSSIA, LET PEOPLE GO!”

Vast parts of the city have been destroyed by shelling and, moments after Zelensky’s address, there were fresh reports that Russian forces attacked supposedly safe evacuation routes out of Mariupol. Earlier Tuesday, Moscow’s envoy to the United Nations promised to open humanitarian corridors to allow people to flee from Mariupol and other besieged cities.

Ukraine’s foreign ministry posted on social media: “Ceasefire violated! Russian forces are now shelling the humanitarian corridor from Zaporizhzhia to Mariupol. 8 trucks + 30 buses ready to deliver humanitarian aid to Mariupol and to evac civilians to Zaporizhzhia. Pressure on Russia MUST step up to make it uphold its commitments.”

Russian forces have repeatedly breached ceasefire agreements meant to allow civilians to escape Mariupol, and the Red Cross warned this week that one route out of the city was booby-trapped with land mines. However, BBC News reported that some people were being allowed to leave other cities, including Sumy in the northeast and Irpin, near Kyiv.

While his forces were shelling Ukrainians, President Vladimir Putin paid a hollow tribute to International Women’s Day, saying it would be a holiday full of “the brightest feelings” and “sincere words of admiration and gratitude” to Russian women and girls, according to the Washington Post.

Zelensky, meanwhile, said said he wasn’t able to congratulate Ukrainian women over the holiday “when there are so many deaths.”