Ending days of relative calm in the Ukrainian capital, Russia on Thursday bombarded Kyiv — as the head of the United Nations visited and met with President Volodymyr Zelensky — while also ramping up attacks along the besieged country’s eastern front, Ukrainian officials said.

The attacks came as President Biden announced he was seeking $33 billion in additional military and humanitarian aid for Ukraine and also sought congressional approval to seize the assets of Russian oligarchs who support Russian President Vladimir Putin and use the funds to help Ukraine.

“The cost of this fight is not cheap, but caving to aggression is more costly,” Biden said in announcing the new package, to be spent over the next five months.

Thursday’s missile attacks on Kyiv hit an apartment building, injuring several people — many trapped in rubble — and killing at least one, city officials said. The explosions came as U.N. Secretary-General António Guterres was winding up a day of meetings in the capital with Zelensky and others to discuss the evacuation of civilians from the obliterated southern port city of Mariupol, among other issues.

The new attacks “prove that we must not drop our vigilance,” Zelensky said. “We must not think that the war is over.”