(NewsNation Now) — Russian forces, after seizing two Ukrainian nuclear power plants, are now advancing toward a third, Ukraine’s president Volodymyr Zelenskyy said during a call with U.S. senators Saturday.

The third plant currently under threat is the Yuzhnoukrainsk nuclear power plant, Zelenskyy said.

This news comes after Russia attacked Ukraine’s largest nuclear power plant Friday.

Technical safety systems are intact and radiation levels are normal at the Zaporizhzhia nuclear power plant the day after the attack, according to the country’s nuclear regulator.

Ukraine has four nuclear plants with a total of 15 reactors.

The U.S. Embassy in Ukraine is calling Russia’s actions at the Zaporizhzhia plant a war crime, though the Pentagon is not yet doing so, its spokesman told NewsNation.

Also during Saturday’s 300-person call, Zelenskyy made a “desperate plea” to U.S. senators to send more planes to help the country fight, and urged lawmakers to sanction Russia’s oil and gas sector and suspend credit card access. He backed an idea to ban Russian oil imports to the U.S. that’s been gaining support in Congress.

Another person on the call, according to the Associated Press, said Congress is working on a $10 billion package of military and humanitarian aid to Ukraine.

Saturday marks the tenth day of the war in Ukraine, which started last week after Russia’s unprovoked attacks on the other country.

Russian President Vladimir Putin’s actions have sparked worldwide condemnation, from global leaders and protestors across nations. On Monday, a next round of talks is scheduled between Ukraine and Russia, Ukrainian official Davyd Arakhamia said.

A vast Russian armored column threatening Ukraine’s capital remained stalled outside Kyiv Saturday, but Russia’s military has launched hundreds of missiles and artillery attacks on cities and other sites across the country.

Ukrainian forces held key cities in the central and southeastern part of the country while Russian troops continued to block and keep encircling Kharkiv, Mykolaiv, Chernihiv and Sumy, according to Zelenskyy.

The Ukrainian government released a video showing a Russian military plane falling from the sky and crashing on Saturday.

“We’re inflicting losses on the occupants they could not see in their worst nightmare,” Zelenskyy said. “This is horrible…Guys 18, 20 years old … soldiers who weren’t even explained what they were going to fight for.”

Ukrainian Foreign Minister Dmytro Kuleba echoed the president’s assertion that Russia has lost more than 10,000 troops.

The claim could not be independently verified the Associated Press reported. The Russian military doesn’t offer regular updates on their casualties. On Wednesday, they revealed a death toll of 498.

“Russians keep bearing devastating losses on the ground, and I cannot understand how mothers, wives and daughters of these Russian soldiers bear this pain, seeing how President Putin sends more and more of their beloved ones to Ukraine,” Kuleba said.

Kuleba added, “Ukraine is bleeding but Ukraine has not fallen and stands (with) both feet on the ground.”

Even though Russian defense officials announced a cease-fire in Mariupol, Ukraine officials say the city remained under attack.

“The Russian side is not holding to the cease-fire and has continued firing on Mariupol itself and on its surrounding area,” Kyrylo Tymoshenko, the deputy head of Zelenskyy’s office, said. “Talks with the Russian Federation are ongoing regarding setting up a cease-fire and ensuring a safe humanitarian corridor.”

An earlier statement from the Russian Defense Ministry said it had agreed on evacuation routes with Ukrainian forces for Mariupol, a strategic port in the southeast and for the eastern city of Volnovakha.

City officials, though, report that shelling has continued despite the deal.

Mariupol deputy mayor Serhiy Orlov told the BBC that the Russians “continue to use hard artillery and rockets to bomb Mariupol.”

Because Mariupol is still under fire, Tymoshenko said, evacuations have halted there.

KYIV, Ukraine —

Kuleba also said in a video message released by the Ukrainian government that the Russians had lost dozens of aircraft and hundreds of armored vehicles.

The U.N.’s Refugee Agency said on Twitter that 1.3 million people have now fled Ukraine to seek safety. At least 351 civilians have been confirmed killed since the fighting began, but the U.N is saying the true number of people who died is likely much higher. In a warning of a hunger crisis yet to come, the U.N. World Food Program says millions of people inside Ukraine, a major global wheat supplier, will need food aid “immediately.”

U.N. Secretary-General Antonio Guterres says the United Nations is committed to scaling up its humanitarian operations to help both those who have stayed in Ukraine and the millions who have fled.

Guterres relayed the promise to Ukrainian Foreign Minister Dmytro Kuleba in a phone call on Saturday, U.N. spokesman Stephane Dujarric said.

Dujarric said the two also discussed the conditions for safely evacuating civilians, including foreigners, from combat zones.

The U.N. estimates that the 12 million people who have stayed in Ukraine and those who have fled to neighboring countries will need humanitarian aid in the coming months.

Meanwhile, diplomatic efforts continued in an effort to stop the crisis Saturday. U.S. Secretary of State Antony Blinken arrived in Poland to meet with the prime minister and foreign minister. During his visit, Blinken heard harrowing tales from mothers about their journeys, according to the Associated Press.

Tatyana, 58, who wouldn’t give her last name, came with her daughter, Anna, 37 and her 6- and 1-year-old daughters, Katya and Kira, from Kharkiv, about 621 miles away. “They were shooting on the street,” Tatyana said. Anna said her home had been destroyed by a shell or a rocket.

She was in the basement with her daughters when the explosion happened, the AP reported. “They should be in school,” Anna said. “They are children, they don’t understand.”

On Monday, a third round of talks is scheduled between Ukraine and Russia, Ukrainian official Davyd Arakhamia said.

NATO has ruled out establishing a no-fly zone over non-member Ukraine, saying it could provoke widespread war in Europe. Zelenskyy has lashed out at NATO over this, warning that “all the people who die from this day forward will also die because of you.”

A no-fly zone would bar all unauthorized aircraft from flying over Ukraine. Putin said Moscow will consider any third-party declaration of a no-fly zone as  “participation in the armed conflict.”

Russia would view “any move in this direction” as an intervention that “will pose a threat to our service members,” Putin said. He said Western sanctions were akin to war.

Russia continues to crack down on independent media reporting on the war, also blocking Facebook and Twitter, and more outlets say they are pausing their work inside the country.

The U.N. Security Council will hold an open meeting Monday on the worsening humanitarian situation in Ukraine as the Russian offensive intensifies.

This story is developing, refresh for updates.