Western governments were preparing Wednesday to impose tougher sanctions against Russia, as Ukraine documents and investigate 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.