Ukrainian authorities struggled to determine the fate of hundreds of civilians sheltering in a theater destroyed by a Russian airstrike in the besieged city of Mariupol, as officials reported that Russian artillery destroyed additional civilian structures in another frontline city Thursday.

A glimmer of hope emerged when an official stated that some people had survived the Mariupol theater strike.

According to a photo released by Mariupol's city council, an entire section of the large, three-story theater collapsed following Wednesday evening's strike. Several hundred people took refuge in the basement of the building, seeking safety from Russia's three-week siege of the strategic Azov Sea port city.

According to images released by the Maxar space technology company, the pavement in front of and behind the once-elegant theater was marked with massive white letters spelling out "CHILDREN" in Russian as recently as Monday.

The entrance to the shelter had been buried by rubble inside the theater, and the number of casualties was unknown, Pavlo Kyrylenko, the head of the Donetsk regional administration, said on Telegram. Sergiy Taruta, a Ukrainian parliament member and former governor of the Donetsk region, which includes Mariupol, later stated on Facebook that some people escaped alive from the destroyed building. He did not provide any additional information.

According to Kyrylenko, Russian airstrikes also struck a municipal swimming pool complex in Mariupol, where civilians, including women and children, had sought refuge. "Now there are pregnant women and women with children trapped beneath the rubble," he wrote, though the death toll was not immediately available.

Volodymyr Zelenskyy, Ukraine's president, appealed for additional assistance to his country in a video address to German lawmakers on Thursday, claiming that thousands of people have been killed in the conflict that began nearly a month ago including 108 children.

Additionally, he alluded to the dire situation in Mariupol. "Everything is a target for them," he said, including "a theater that provided shelter for hundreds of people yesterday."

According to Bundestag deputy speaker Katrin Goering-Eckardt, the address began late due to a technical issue caused by "an attack in the immediate vicinity" of the location from which Zelenskyy was speaking.

Zelenskyy's address to the Bundestag came a day after delivering a video address to the United States Congress, garnering several standing ovations as he pleaded for additional assistance.

The Russian defense ministry denied that the theater or any other location in Mariupol had been bombed on Wednesday.

According to Zelenskyy's office, Russia conducted additional airstrikes on Mariupol early Thursday morning and artillery and airstrikes across the country overnight, including in the capital's Kalynivka and Brovary suburbs. There was no word on casualties immediately.

In Kyiv, where residents have been huddling in homes and shelters, an apartment building caught fire early Thursday after being struck by remnants of a downed Russian rocket. According to emergency services, one person was killed, and at least three others were injured. Firefighters evacuated 30 people from the 16-story building's top floors within an hour and extinguished the blaze.

According to Merefa mayor Veniamin Sitov, Russian artillery destroyed a school and a community center on Thursday in Merefa, a city near the northeastern city of Kharkiv. There have been no reports of civilian casualties. The Kharkiv region has been bombarded heavily as stalled Russian forces attempt to advance.

Six nations have requested a meeting of the United Nations Security Council on Ukraine on Thursday afternoon, ahead of an expected vote Friday on a Russian resolution demanding protection for Ukrainian civilians "in vulnerable situations," but making no mention of Moscow's role in the war.

"Russia is committing war crimes and targeting civilians," the United Kingdom's United Nations Mission tweeted announcing the meeting, which was also attended by the United States, France, and others. "Russia's illegal war against Ukraine is a danger to us."

President Vladimir Putin of Russia went on television Wednesday to castigate Russians who do not support him.

Russians "will always be able to tell true patriots from scum and traitors and will spit them out like a gnat that landed in their mouths," he said. "I am convinced that such an inevitable and natural purification of society will only serve to strengthen our country."

He asserted that the West is fomenting civil unrest by using a "fifth column" of traitorous Russians.

"And there is only one objective, as I have already stated — the destruction of Russia," he continued.

The speech appeared to warn that his authoritarian rule, which had already become more repressive since the invasion began on Feb. 24, shutting down Russian news outlets and arresting protesters, could become even more so.

As evidence, Russian law enforcement announced the first known criminal cases under a new law authorizing 15-year prison sentences for posting what is deemed to be "false information" about the Ukraine war. Veronika Belotserkovskaya, a Russian-language cookbook author and blogger, based in the United States, was among those charged.

However, it came amid signs that negotiations were finally progressing.

After Tuesday's meeting, Russian Foreign Minister Sergey Lavrov stated that the two sides were "seriously discussing" granting Ukraine a neutral military status. In contrast, Zelenskyy noted that Russia's demands for an end to the war were becoming "more realistic."

Wednesday's videotaped discussions appeared to delve deeper into technical details.

Mikhailo Podolyak, a Zelenskyy adviser, stated that Ukraine demanded a cease-fire, the withdrawal of Russian troops, and security guarantees from several countries.

"This can only be accomplished through direct communication" between Zelenskyy and Putin.

According to an official in Zelenskyy's office, the primary topic of discussion was whether Russian troops would remain in separatist regions of eastern Ukraine following the war's conclusion and where the borders would be.

According to the official, who spoke on the condition of anonymity to discuss the sensitive talks, Ukraine insists on the inclusion of one or more Western nuclear powers in the negotiations and on a legally binding document providing Ukraine with security guarantees. The official stated that Ukraine was willing to discuss a neutral status in exchange.

Russia has demanded that NATO commit to never admitting Ukraine or stationing forces there.

Earlier Wednesday, Zelenskyy appeared via video before the United States Congress and pleaded with America for additional weapons and stricter sanctions against Russia, saying: "We need you right now."

President Joe Biden announced that the US would provide Ukraine with an additional $800 million in military assistance. He also denounced Putin as a "war criminal," his strongest condemnation of the Russian leader since the invasion began.

Although Moscow's ground assault on Ukraine's capital appeared primarily stalled, Putin previously stated that the operation was proceeding "successfully and in strict accordance with pre-approved plans." He also criticized Western sanctions against Moscow, accusing them of attempting to "squeeze us, to put pressure on us, to transform us into a weak, dependent country."

According to the United Nations, the fighting has forced more than 3 million people to flee Ukraine. Although Ukraine has stated that thousands of civilians have died, the death toll remains unknown.

Nowhere has suffered more than the encircled city of Mariupol, where local officials estimate that missile strikes and shelling have killed over 2,300 people. The southern seaport, which has a population of 430,000, has been under attack for nearly the three-week war, with residents struggling for food, water, heat, and medicine.

Dr. Valeriy Drengar pulled back a blanket to reveal the body of a 22-day-old infant, using the flashlight on his cellphone to illuminate a hospital basement. Additional wrapped bodies appeared to be children as well.

"These are the people we were unable to rescue," Drengar explained.