ANDRIIVKA, Ukraine (AP) — Ukraine gathered its dead and collected evidence of Russian atrocities on the ruined outskirts of Kyiv, as the two sides geared up Wednesday for what could become a climactic battle by Moscow’s forces to seize the country’s industrial east.

As America and its Western allies moved to impose new sanctions against the Kremlin in retaliation for what they branded war crimes, President Zelensky said Russian forces were trying to push deep into Ukraine in the east, but the Ukrainian army was holding them back.

“The fate of our land and of our people is being decided. We know what we are fighting for. And we will do everything to win,” Mr. Zelensky said.

Ukrainian officials have stepped up calls for civilians to evacuate westward from towns near the front line ahead of the anticipated Russian offensive, and some essential services were being moved away. Local authorities in Sloviansk said postal and pension operations were clearing out and bank branches in town were shutting down.

A Western official, speaking on condition of anonymity to discuss intelligence, said it will take Russia as much as a month to regroup for a major push on eastern Ukraine. Almost a quarter of its battalion tactical groups in the country have been rendered “non-combat-effective” and have either withdrawn or merged with other units, the official said.

In the scarred and silent streets of Bucha and other towns around Ukraine’s capital where Russian forces withdrew over the past several days, investigators sought to document what appeared to be widespread killings of civilians. Some had evidently been shot at close range, while others were found with their hands bound or their flesh burned.

At a cemetery in Bucha, workers began to load more than 60 bodies apparently collected over the past day into a grocery shipping truck for transport to a facility for further investigation. A few of the black body bags were not fully closed. A glimpse showed the bloodied face of a young adult. Another revealed a pair of white sneakers.

More bodies were yet to be collected in Bucha, days after the Russian retreat. The Associated Press saw two in a house in a silent neighborhood. From time to time there was the muffled boom of workers clearing the town of mines and other unexploded ordnance.

In Andriivka, a village about 40 miles west of Kiev, two police officers from the nearby town of Makariv came Tuesday to identify a man whose body was in a field beside tank tracks. Officers found 20 bodies in the Makariv area, Captain Alla Pustova said.

Andriivka residents said the Russians arrived in early March and took locals’ phones. Some people were detained, then released; others met unknown fates. Some described sheltering for weeks in musty, cramped cellars normally used for storing vegetables for winter.

With the sixth week of the war drawing to a close, the soldiers were gone, and Russian armored personnel carriers, a tank and other vehicles sat destroyed on both ends of the road running through the village. Several buildings were reduced to mounds of bricks and corrugated metal. Residents struggled without heat, electricity or cooking gas.

“First we were scared, now we are hysterical,” said Valentyna Klymenko, 64. She said she, her husband and two neighbors weathered the siege by sleeping on stacks of potatoes covered with a mattress and blankets. “We didn’t cry at first. Now we are crying.”

To the north of the village, in the town of Borodyanka, rescue workers combed through the rubble of apartment blocks, looking for bodies. Mine-disposal units worked nearby.

The Kremlin has insisted its troops have committed no war crimes, charging that the images out of Bucha were staged by the Ukrainians.

Thwarted in their efforts to take the capital and forced to withdraw, President Putin’s troops, along with mercenaries, are now pouring into the Donbas, Ukraine’s mostly Russian-speaking industrial heartland in the east.

Overnight, Russian forces attacked a fuel depot and a factory in the Dnipropetrovsk region, just west of the Donbas, authorities said. In the Luhansk region, which is part of the Donbas, Russian shelling Wednesday set fire to at least 10 multi-story buildings and a mall in the town of Sievierodonetsk, the regional governor reported. There was no immediate word on deaths or injuries.

Ukrainian forces have been fighting Russia-backed separatists in Luhansk and the other Donbas region, Donetsk, since 2014. Ahead of its February 24 invasion, Moscow recognized the regions as independent states.

Ukrainian authorities have said the bodies of at least 410 civilians have been found in towns around Kiev, and Associated Press journalists in Bucha counted dozens of corpses in civilian clothes and interviewed Ukrainians who told of witnessing atrocities.

In a video address Tuesday to the United Nations Security Council, Mr. Zelensky said that civilians had been tortured, shot in the back of the head, thrown down wells, blown up with grenades in their apartments and crushed to death by tanks while in cars.

He said that those who gave the orders and those who carried them out should face war crimes charges in front of a Nuremberg-type tribunal.

In reaction to the alleged atrocities, America announced sanctions against Mr. Putin’s two adult daughters and said it is toughening penalties against Russian banks. Britain banned investment in Russia and pledged to end its dependence on Russian coal and oil by the end of the year.

The European Union was also expected to take additional punitive measures, including an embargo on coal.