CHERNIHIV, Ukraine (NewsNation) — Ukrainian leaders predict more gruesome discoveries would be made in reclaimed cities and towns after retreating Russian forces left behind crushed buildings, streets strewn with destroyed cars and mounting civilian casualties that drew condemnation across the globe.

President Volodymyr Zelenskyy said the horrors of Bucha, a town north of Kyiv where bodies of people killed at close range were found on streets and in basements, already had surfaced in a worse way in Borodianka, another settlement outside the capital.

“And what will happen when the world learns the whole truth about what the Russian troops did in Mariupol?” Zelenskyy said late Thursday, referring to the besieged southern port that has seen some of the greatest suffering since Russia invaded Ukraine. “There on every street is what the world saw in Bucha and other towns in the Kyiv region after the departure of the Russian troops. The same cruelty. The same terrible crimes.”

After failing to take Kyiv, Russia shifted its focus to the Donbas, a mostly Russian-speaking, industrial region in eastern Ukraine where Moscow-backed rebels have fought Ukrainian forces for eight years. Ukrainian officials warned residents this week to leave as soon as possible.

In a sign of the intense fighting expected to come, Ukrainian authorities said a rocket strike Friday killed at least 52 people and wounded over 100 at a train station in Kramatorsk, a city in the eastern Donetsk region, that was being used to evacuate civilians.

Photos from the station in Kramatorsk showed the dead covered with tarps, and the remnants of a rocket with the words “For the children” painted on it in Russian. About 4,000 civilians had been in and around the station, heeding calls to leave before fighting intensifies in the Donbas region, the office of Ukraine’s prosecutor-general said.

Regional governor Pavlo Kyrylenko said thousands of people were at the train station during the strike, preparing to head to safer regions.

A Kremlin spokesman acknowledged that Russia has suffered major troop casualties during its six-week military operation in Ukraine.

“Yes, we have significant losses of troops, and it is a huge tragedy for us,” Kremlin spokesman Dmitry Peskov told Sky News.

Peskov also hinted the fighting might be over “in the foreseeable future,” telling Sky that Russian troops were “doing their best to bring an end to that operation.”

Spurred by reports that Russian forces committed atrocities in areas surrounding the capital, NATO nations agreed to increase their supply of arms after Ukraine’s foreign minister pleaded for weapons from the alliance and other sympathetic countries to help face down an expected offensive in the east.

Bucha Mayor Anatoliy Fedoruk said investigators found at least three sites of mass shootings of civilians during the Russian occupation. He said most victims died from gunshots, not from shelling, and some corpses with their hands tied were “dumped like firewood” into mass graves, including one at a children’s camp.

Fedoruk said 320 civilians were confirmed dead as of Wednesday, but he expected more as bodies are found in the city that was home to 50,000 people. Only 3,700 remain, he said.

Zelenskyy said Bucha’s horrors might be only the beginning in his nightly address. In the northern city of Borodianka, just 20 miles northwest of Bucha, he warned of even more casualties, saying, “There, it is much more horrible.”

Ukrainian and several Western leaders have blamed the massacres on Moscow’s troops. The weekly magazine Der Spiegel reported Germany’s foreign intelligence agency intercepted radio messages among Russian soldiers discussing the killings of civilians. Russia has falsely claimed that the scenes in Bucha were staged.

The World Health Organization has verified more than 100 “attacks on health care” in Ukraine since the country was first invaded more than a month ago, the organization’s top official said.

There have been at least 103 attacks on hospitals and other health care facilities in the country, and at least 73 were killed and 51 injured in those incidents, said WHO Director-General Dr. Tedros Adhanom Ghebreyesus, speaking at a news conference in Washington, D.C.

The toll includes medical workers as well as patients, he said.

He praised the United States for supporting international health efforts in Ukraine, including delivering more than 180 metric tons of medical supplies to hard-hit areas. “We are outraged that attacks on health care (in Ukraine) continue,” he said.

On Thursday, a day after Russian forces began shelling their village in the southern Mykolaiv region, Sergei Dubovienko, 52, drove north in his small blue Lada with his wife and mother-in-law to Bashtanka, where they sought shelter in a church.

“They started destroying the houses and everything” in Pavlo-Marianovka, he said. “Then the tanks appeared from the forest. We thought that in the morning there would be shelling again, so I decided to leave.”

Hundreds of people have fled villages in the Mykolaiv and Kherson regions that are either under attack or occupied by Russian forces.

Marina Morozova and her husband fled from Kherson, the first major city to fall to the Russians.

“They are waiting for a big battle. We saw shells that did not explode. It was horrifying,” she said.

Morozova, 69, said only Russian television and radio was available. The Russians handed out humanitarian aid, she said, and filmed the distribution.

Anxious to keep moving away from Russian troops, the couple and others boarded a van that would take them west. Some will try to leave the country, while others will remain in quieter parts of Ukraine.

The United Nations estimates the war has displaced at least 6.5 million people within the country.

The U.N. refugee agency, UNHCR, said that more than 4.3 million, half of them children, have left Ukraine since Russia launched its invasion on Feb. 24 and sparked Europe’s largest refugee crisis since World War II.

The International Organization for Migration estimates more than 12 million people are stranded in areas of Ukraine under attack.

On Thursday, the United Nations’ humanitarian chief told The Associated Press that he’s “not optimistic” about securing a cease-fire after meeting with officials in Kyiv and Moscow this week, given the lack of trust between the sides. He spoke hours after Russian Foreign Minister Sergey Lavrov accused Ukraine of backtracking on its proposals made over Crimea and Ukraine’s military status.

Two top European Union officials and the prime minister of Slovakia traveled to Kyiv on Friday, looking to shore up the E.U.’s support for Ukraine. Prime Minister Eduard Heger said he, E.U. Commission President Ursula von der Leyen and E.U. foreign policy chief Josep Borrell have trade and humanitarian aid proposals for Zelenskyy and his government.

Part of that, Heger said, is “to offer options for transporting grains, including wheat.” Ukraine is a major world wheat supplier and Russia’s war on Ukraine is creating shortages, notably in the Middle East.

Western nations have stepped up sanctions, and the Group of Seven major world powers warned that they will keep adding measures until Russian troops leave Ukraine.

The U.S. Congress voted Thursday to suspend normal trade relations with Russia and ban the importation of its oil. At the same time, the E.U. approved other new steps, including an embargo on coal imports. The U.N. General Assembly voted to suspend Russia from the world organization’s leading human rights body.

U.S. President Joe Biden said the U.N. vote demonstrated how “Putin’s war has made Russia an international pariah.” He called the images coming from Bucha “horrifying.”

“The signs of people being raped, tortured, executed — in some cases having their bodies desecrated — are an outrage to our common humanity,” Biden said.

Meanwhile, the E.U. imposed sanctions on two adult daughters of Russian President Vladimir Putin as part of a new package of measures targeting Russia for its invasion of Ukraine, according to two E.U. officials.

The E.U. included Maria Vorontsova and Katerina Tikhonova in its updated list of individuals facing assets freeze and travel bans. The two E.U. officials from different E.U. member countries spoke on condition of anonymity to The Associated Press because the updated list of sanctions has not been published yet.

The move from the European bloc follows a similar move two days earlier by the United States.

The Associated Press contributed to this report.