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

A Russian missile airstrike was reported in different areas of Ukraine Sunday evening.

Sixteen Russian Tu-95 bombers were reported in the air from various airfields and explosions were reported in the Dnipropetrovsk region of Ukraine at 10:51 p.m. local time.

“Presumably, Kh-101 cruise missiles are actively flying at the Pavlograd-1 and Pavlograd-2 railway stations, where trains with APU (Ukrainian Armed Forces) equipment and people were located,” a Russian Telegram channel, Military Chronicle, said.

Several explosions were heard in the city of Pavlograd, in the Dnipropetrovsk region, local Ukrainian media reported.

An air alert was announced for the region at 9:30 p.m. local time and about 10:00 p.m., social networks began to report explosions in Pavlograd.

According to local media, repeated explosions were heard in the city at 10:20 p.m.

The strikes destroyed Ukrainian anti-aircraft missiles for the S-300 complex on Pavlograd, Russian Telegram channel Intel Slava reported.

S-300s are long-range surface-to-air missiles.

Supply vehicles with reserve ammunition that belong to the Ukrainian Armed Forces were also hit, the channel said, citing eyewitness accounts.

Intel Slava is funded by the Russian government.

“The detonation of rockets has been going on for almost an hour,” the Intel Slava post said.

It's unclear how many people were injured or killed.

-ABC News' Fidel Pavlenko and Anastasia Bagaeva