A second round of talks between Russian and Ukrainian negotiators will be held at the previously planned venue in neighboring Belarus on Thursday at around 3 p.m. local time (7 a.m. ET), according to Vladimir Medinsky, head of the Russian delegation and aide to Russian President Vladimir Putin.

"The talks will take place -- we are now in contact with the Ukrainian side -- at the same venue where they were planned, on the territory of the Brest region of Belarus," Medinsky told reporters Thursday, adding that Russian negotiators are "waiting calmly."

"I think the talks will begin at 3 p.m.," he said.

Ukraine's presidential advisor Mykhailo Podolyak from the Ukrainian delegation later posted a photo of himself on his official Twitter account on Thursday, saying they were en route via helicopter to the talks in Belarus

-ABC News' Patrick Reevell and Tanya Stukalova

Russian Foreign Minister Sergey Lavrov wouldn't comment on civilian deaths from Russia's invasion of Ukraine when pressed during an interview Thursday with ABC News' George Stephanopoulos on "Good Morning America."

"I cannot comment," Lavrov said, adding that there are "a great deal" of "conjectures."

Ukraine claimed Thursday to have raised its flag over the town of Bucha, close to the Ukrainian capital where some of the most intense fighting has been taking place in recent days and where Russia's push south on Kyiv appears to have stalled.

A video posted on the official Facebook page of the Ukrainian Armed Forces' ground troops purportedly shows soldiers hoisting the national flag outside Bucha's town hall. The town is just a few miles north of the edge of Kyiv and about 15 miles from the center of the capital. Fighting is reported to be ongoing nearby and, in the video, an explosion can be heard in the distance as they raise the blue and yellow flag.

-ABC News' Yulia Drozd

Ukraine is asking the International Atomic Energy Agency (IAEA) to call on NATO to close access to the airspace over the country's Chernobyl nuclear power plant and the surrounding exclusion zone.

The deserted exclusion zone around the Chernobyl nuclear power plant, where the world's worst nuclear accident took place in 1986, was seized by Russian forces last week.

A joint appeal to the IAEA was signed Wednesday by Ukrainian Energy Minister Herman Galushchenko, Oleh Korikov, head of the State Nuclear Regulatory Inspectorate of Ukraine, and Petro Kotin, head of Ukraine's state nuclear energy company Energoatom.

"The fact of the seizure of the world-famous Chernobyl nuclear power plant has all the hallmarks of an act of nuclear terrorism committed against Chernobyl nuclear facilities and its personnel by Russian military units," they said in the appeal.

-ABC News' Yulia Drozd

While Poland has been welcoming refugees fleeing the destruction in Ukraine, the country will eventually meet its limit on how many people it can take in, Konrad Fijolek, president of Rzeszow, Poland, a city about 60 miles from the Ukrainian border, told ABC News.

Like many cities that border Ukraine, Rzeszow, a town of about 180,000 people, has become a pathway to safety and a lifeline for millions of refugees flooding across the border from Ukraine.

Poland will be able to receive about 1.5 million people, but any more will put the country under strain, Fijolek said.

"If a million or more come, we won't be able to cope," he said.

Some estimates suggest as many as 4 million people could leave Ukraine due to the conflict, but most of the major cities in the country are already full — and officials are attempting to move refugees into smaller cities, a feat that is "not easy," Fijolek said.

So far, all the shelters set up in Poland are temporary, he added.

"We would like to avoid the view of refugee camps here," he said. "We would like people who are escaping from the war to think that what awaits here is proper camp not camps."

In addition, the mental state among the people in Poland is continuing to deteriorate, Fijolek said.

"We as local leaders would like to send the message that if there's any possible action to stop the war [find it] and then try to negotiate, because every day at the border we can see the human tragedy," he said.

-ABC News' Chris Donato and Marcus Moore