BUCHA, Ukraine >> Western governments were preparing Wednesday to impose tougher sanctions against Russia, as Ukraine documents and investigates widespread killings of civilians and other alleged war crimes.

Ukrainian President Volodymyr Zelenskyy kept up demands for war-crimes trials for Russian troops and their leaders while warning they were regrouping for fresh assaults on Ukraine’s east and south. The Ukraine military said Russia was preparing for an offensive in Ukraine’s east, with the aim “to establish complete control over the territory of Donetsk and Luhansk regions.”

Overnight, Russian forces attacked a fuel depot and a factory in Ukraine’s Dnipropetrovsk region, the region’s governor Valentyn Reznichenko said on the messaging app Telegram early Wednesday. The number of casualties was unclear.

“The night was alarming and difficult. The enemy attacked our area from the air and hit the oil depot and one of the plants. The oil depot with fuel was destroyed. Rescuers are still putting out the flames at the plant,” Reznichenko wrote.

Police in the Romanian capital Bucharest said a car rammed the gate of the Russian Embassy early Wednesday, bursting into flames and killing the driver. There was no immediate information on a possible motive or other details.

In Ukraine’s eastern Luhansk region, shelling of Rubizhne city on Tuesday killed one person and injured five more, its governor Serhiy Haidai said on Telegram.

Parts of Donetsk and Luhansk have been under control of Russia-backed rebels since 2014 and are recognized by Moscow as independent states. So far, Ukrainian forces have been holding back Russian troops trying to push east but remain outnumbered in both troops and equipment, Zelenskyy said in a video address to his country late Tuesday.

Evidence of what appears to be intentional killings of civilians in Bucha and other towns before Russian forces withdrew from the outskirts of Kyiv has drawn a global outcry. Western nations have expelled scores of Moscow’s diplomats and are expected to roll out more sanctions Wednesday.

They would include a ban on all new investment in Russia, a senior U.S. administration official said, speaking on condition of anonymity to discuss the upcoming announcement.

The EU’s executive branch, meanwhile, proposed a ban on coal imports from Russia, worth an estimated 4 billion euros ($4.4 billion) per year. It would be the first time the 27-nation bloc has sanctioned the country’s lucrative energy industry over the war.

In an address Tuesday to the U.N. Security Council, Zelenskyy said civilians in towns around Kyiv were 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.

Those who carried out the killings and those who gave the orders “must be brought to justice immediately for war crimes” in front of a tribunal similar to the one established at Nuremberg after World War II, he said.

“But we don’t have a choice — the fate of our land and of our people is being decided,” he said. “We know what we are fighting for. And we will do everything to win.”

Russia has insisted its troops have committed no war crimes.

Moscow’s U.N. ambassador, Vassily Nebenzia, said “not a single local person” suffered from violence while Bucha was under Russian control. Reiterating Kremlin comments, he said scenes of bodies in the streets were “a crude forgery” staged by the Ukrainians.

In the still largely empty streets of Bucha, dogs wandered among ruined buildings and burned military vehicles. Officials snapped photos of the corpses before gathering some of them.

Survivors of the monthlong Russian occupation showed investigators bodies of townspeople allegedly shot by Russian troops. Those who hid in their homes during the occupation, many of them beyond middle age, wandered past charred tanks and jagged window panes with plastic bags of food and other humanitarian aid. Red Cross workers checked in on intact homes.

Associated Press journalists in Bucha counted dozens of corpses in civilian clothes and interviewed Ukrainians who told of witnessing atrocities. Also, high-resolution satellite imagery from Maxar Technologies showed many of the bodies laid in the open for weeks while Russian forces were in the town.

The dead in Bucha included a pile of six charred bodies, as witnessed by AP journalists. It was not clear who they were or how they died. One body was probably that of a child, said Andrii Nebytov, head of police in the Kyiv region.

Many of the dead seen by AP journalists appeared to have been shot at close range, and some had their hands bound or their flesh burned.

The AP and the PBS series “Frontline” have jointly verified at least 90 incidents during the war that appear to violate international law. The War Crimes Watch Ukraine project is looking into apparent targeted attacks and indiscriminate ones.

U.S. Secretary of State Antony Blinken said images from Bucha revealed “not the random act of a rogue unit” but “a deliberate campaign to kill, to torture, to rape, to commit atrocities.” He said the reports of atrocities were “more than credible.”

The chief prosecutor for the International Criminal Court at The Hague opened an investigation a month ago into possible war crimes in Ukraine.

Elsewhere in Ukraine, in Borodyanka, northwest of Kyiv, a 25-year-old, Dmitriy Yevtushkov, searched the rubble of apartment buildings and found that only a photo album remained from his family’s home.

In the besieged southern city of Mykolaiv, a passerby stopped briefly to look at the bright blossoms of a shattered flower stand lying among bloodstains, the legacy of a Russian shell that killed nine people in the city’s center. The onlooker sketched the sign of the cross in the air, and moved on.

British defense officials said Wednesday that 160,000 people remain trapped by Russian air strikes and heavy fighting in the besieged southern port city of Mariupol.

The Ministry of Defense intelligence update said the city has “no light, communication, medicine, heat or water.” It accused Russian forces of deliberately preventing humanitarian access, “likely to pressure defenders to surrender.”

The International Committee of the Red Cross’s efforts to get humanitarian convoys into Mariupol have failed. Ukraine’s Deputy Prime Minister Iryna Vereshchuk said Russian forces stopped buses accompanied by Red Cross workers from traveling to Mariupol, which had a pre-war population of over 400,000. She said Russian troops allowed 1,496 civilians to leave the Sea of Azov port on Tuesday.

While both Ukrainian and Russian representatives sent optimistic signals following their latest round of talks a week ago, Russian Foreign Minister Sergey Lavrov said Moscow will not accept a Ukrainian demand that a prospective peace deal include an immediate pullout of troops followed by a Ukrainian referendum on the agreement.