At least 21 people were killed and 48 injured by shelling in the Kherson region on Wednesday, Ukrainian officials said, as the death toll continues to rise.

A railway station and market in the city of Kherson were hit in strikes, which occurred across the Kherson region in southern Ukraine, officials said.

"A railway station and a crossing, a house, a hardware store, a grocery supermarket, a gas station -- do you know what unites these places? The bloody trail that [Russia] leaves with its shells, killing civilians in Kherson and Kherson region," Ukrainian President Volodymyr Zelenskyy said on Twitter.

All the victims were civilians, Zelenskyy said.

An ambulance was also damaged in the strikes, according to Ukrainian Prosecutor General Andriy Kostin.

"No military objects here. Just civilians, including children," Kostin said on Twitter.

At least one person was killed and three injured in the strike on the railway station, officials previously said.

The Biden administration has announced a new $300 million military aid package for Ukraine.

The package includes additional ammunition for U.S.-provided High Mobility Artillery Rocket Systems, as well as "additional howitzers, artillery and mortar rounds, and anti-armor capabilities that Ukraine is using to push back against Russia’s unprovoked war of aggression," the Department of Defense said in a statement.

This marks the Biden administration’s 37th drawdown of equipment from Defense Department inventories for Ukraine since August 2021.

Ukrainian President Volodymyr Zelenskyy rejected Russia's claim that his country was involved in the drone attack on the Kremlin early Wednesday.

Zelenskyy, who is currently in Finland, said the claim was the prelude to a "large-scale terrorist attack" from Russia.

"First of all, Ukraine wages an exclusively defensive war and does not attack targets on the territory of the Russian Federation," Zelenskyy said in a statement. "What for? This does not solve any military issue. But it gives RF grounds to justify its attacks on civilians."

Zelenskyy went on to say that various attacks in Russia could be the result of "guerrilla activities of local resistance forces."

Russian President Vladimir Putin's spokesman has accused Ukraine of trying to strike Putin's residence in the Kremlin with two drones overnight, but said they were brought down before they could reach their target.

No injuries were reported, Kremlin officials said. Putin was not at the residence at the time, they said.

Videos released on official social media channels appeared to show a drone strike the roof of the Senate Palace at the Kremlin.

The Kremlin said that "the Russian side reserves the right to retaliate whenever and wherever it deems necessary."

-ABC News' Patrick Reevell and Tanya Stukalova

Russian airstrikes targeted several cities across Ukraine early Friday, killing at least 25 people, Ukrainian officials said.

The city of Uman in central Ukraine's Cherkasy Oblast was the worst affected. Several buildings were damaged or destroyed. One of the strikes hit an apartment building, killing at least 23 people, including four children, and injuring another 18 people, according to Cherkasy Oblast Gov. Ihor Taburets. The attack happened at around 4:30 a.m. local time, when most people would have been asleep. An entire section of the nine-story building collapsed, with 27 apartments completely destroyed. There were 109 people who lived in that part of the building, according to Ukrainian police. Rescue teams were expected to spend all day and night searching for survivors in the rubble.

It was the deadliest single attack on civilians in Ukraine since January.

Dnipro, Ukraine's fourth-largest city and a major industrial hub located in southeastern Dnipropetrovsk Oblast, was hit by "high-precision" strikes in the early morning hours, leaving a woman and a 3-year-old child dead, according to Dnipro Mayor Boris Filatov.

Russian strikes also targeted Kyiv, Ukraine's capital and largest city, but there were no reports of any casualties or damages. It was the first such attack on the capital in 51 days, according to the Kyiv City Military Administration. Preliminary data shows 11 cruise missiles and two drones were destroyed in Kyiv's airspace, the city military administration said.

-ABC News' Yulia Drozd, Will Gretsky, Natalia Kushnir and Joe Simonetti