Russia-Ukraine updates: Putin suspends key US-Russia nuclear treaty in speech denouncing West

State Department officials are working to determine the circumstances surrounding the reported strike in Poland, Principal Deputy spokesperson Vedant Patel told reporters.

Calling the reports "incredibly concerning," Patel said they were in close communication with the Polish government and other NATO allies to "gather more information."

"We can't confirm the reports or any of the details at this time. But I can assure you we will determine what happened and what appropriate next steps would be," he said during a briefing Tuesday afternoon.

U.S. national security adviser Jake Sullivan has spoken with Chief of the National Security Bureau of Poland Jacek Siewiera, according to White House National Security Council spokesperson Adrienne Watson.

"We've seen the reports out of Poland and are working with the Polish government to gather more information," Watson said in a statement, also adding that the White House cannot confirm the reports or any details at this time.

President Joe Biden has been briefed on the reports and will be speaking with Polish President Andrzej Duda "shortly," the White House said.

-ABC News' Shannon K. Crawford and Ben Gittleson

Polish Prime Minister Mateusz Morawiecki called a meeting of the Committee of the Council of Ministers for National Security and Defense Affairs amid unconfirmed reports that the NATO ally was hit with stray Russian missiles.

According to Polish media, two stray Russian rockets landed in Polish territory killing two people. The rockets reportedly landed in the Polish town of Przewodów, near the border with Ukraine. These reports have not yet been independently confirmed by ABC News.

Russia denied responsibility for the missile attack, claiming statements by Polish media and officials were a deliberate provocation in order to escalate the situation.

-ABC News' Tom Soufi Burridge, Will Gretsky and Natalia Shumskaia

After Russia hit critical infrastructure in the Lviv region, the area lost 80% of its electricity supply. The city's heating and hot water supply has also stopped and there are mobile service interruptions, according to Andriy Sadovyi, the mayor of Lviv.

Sadovyi warned residents to stay in shelters.

-ABC News' Will Gretsky

Ukrainian President Volodymyr Zelenskyy on Tuesday demanded that Russia end its invasion and reiterated that the territorial integrity of his country is not up for negotiation.

Appearing via video link from Kyiv, Zelenskyy addressed the leaders of the Group of 20 at a summit in Bali as the "dear G-19" -- an apparent snub to Russia, whose foreign minister was attending the event.

"Apparently, one cannot trust Russia's words and there will be no Minsk 3, which Russia would violate immediately after signing," Zelenskyy said, referring to the Minsk 1 and 2 agreements signed in 2014 and 2015, respectively, which aimed to bring an end to fighting at that time. Russia invaded and annexed the Crimean Peninsula in 2014 before using Kremlin-backed proxies to seize territory in the Donbas region of eastern Ukraine.

"I want this aggressive Russian war to end justly and on the basis of the U.N. charter and international law," he added. "Ukraine should not be offered to conclude compromises with its conscience, sovereignty, territory and independence. We respect the rules and we are people of our word."

The Ukrainian president called on the United Nations to dispatch a mission to assess the damages to his country’s energy infrastructure from Russian missile strikes. He said Russian forces should also withdraw from the Zaporizhzhia nuclear power plant -- the largest in Ukraine and in Europe -- so that the International Atomic Energy Agency -- the U.N.'s nuclear watchdog -- can take control of the site together with Ukrainian officials.

In addition, Zelenskyy said his country needs a framework that guarantees the long-term security of his country and he called again for a special tribunal to investigate Russian war crimes in Ukraine. He called this series of proposals Ukraine's "peace formula" and all of them, he said, must be achieved before there is an end to the ongoing war.

"If Russia wants to end this war, let it show it with actions," Zelenskyy said. "We will not allow Russia to wait us out, to grow its forces and then start a new series of terror and global destabilization. I am sure that it is necessary and possible to stop this destructive Russian war now."

In response, Russian Foreign Minister Sergey Lavrov, who was attending the G-20 summit in Bali, called Zelensky's demands "unrealistic."

-ABC News' Tom Soufi Burridge and Patrick Reevell