Russian forces are lashing out at Ukrainian resistance with the relentless siege of the country's cities. The eastern city of Mariupol has seen the worst of it.

But with rescue efforts hampered by constant shelling, it's difficult to know exactly how hard the city has been hit.

Ukrainians say the Russian forces are targeting civilians attempting to flee or hide.

Rescuers struggled to pull survivors from the rubble of this bombed theater. One-hundred-and-thirty people were reportedly saved.

Local officials say more than 350,000 people remain trapped within Mariupol, with 30,000 managing to escape.

There are up to 100 blasts a day, forcing more and more people from their charred apartment blocks.

A woman, who lost her family, said, "We were left even without our underclothes. We dressed in anything we could find. How is it possible? What are these leaders doing? What is it for? What have we done to them?"

The head of the International Committee of the Red Cross, Peter Maurer, says it's hard to get people the help they need. He said, "Allow humanitarian aid in. The parties are obliged under international humanitarian law to ensure people under their control have access to assistance, or to allow aid in."

Russian forces are still a few hours' drive from the capital, Kyiv. And the military seems prepared to bomb the city into submission.

A senior US official says the Russians have now shot more than 1,000 missiles, with civilians increasingly in the crosshairs.

US Secretary of State Antony Blinken says their goal is breaking the people's will. He warns the Russian forces could soon rely on tactics they've used before.

Blinken said, "We believe that Moscow may be setting the stage to use a chemical weapon, and then falsely blame Ukraine to justify escalating its attacks on the Ukrainian people."

The secretary said US experts are documenting and evaluating potential war crimes.

He also said that those efforts will help hold those responsible to account.