Russian troops seized control of a hospital in the city of Mariupol on Tuesday and were holding about 500 people hostage, according to regional leader Pavlo Kyrylenko.

Driving the news: Kyrylenko said on Telegram that the troops drove 400 people into the hospital. One hundred doctors and patients were also inside he said, adding that no one is allowed to leave. He alleged the hostages were being used as human shields.

What they're saying: "It’s impossible to leave the hospital, they are shooting hard," Kyrylenko said.

• He urged the world to respond to these "gross violations of the norms and customs of war, these egregious crimes against humanity," AP writes.

The big picture: Over 2,300 people have been killed during the weeks-long siege of Mariupol, Russian forces' shelling has destroyed buildings including a children's hospital and a mosque, and residents are facing shortages of food, water, heat and medicine, local officials say.

By the numbers: An aide to Ukraine's President Volodymyr Zelensky said some 20,000 people managed to evacuate from Mariupol on Tuesday in "4,000 private vehicles via a designated safe corridor leading to the city of Zaporizhzhia," per AP.

Flashback: Ukraine's President Volodymyr Zelensky previously called the Russian military's bombing of a children's hospital and maternity ward in the city a "war crime" and "proof that the genocide of Ukrainians is taking place."

Go deeper:

• Axios explains Ukraine


• The latest on the Russia-Ukraine crisis