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

After some missed calls, President Joe Biden finally connected with the parents of Wall Street Journal reporter Evan Gershkovich, White House press secretary Karine Jean-Pierre confirmed Tuesday.

"He felt it was really important to connect with Evan's family," she told reporters on Air Force One as the president travels to Ireland.

Meanwhile, National Security Council spokesperson John Kirby said Gershkovich's detention is "pretty fresh" and officials are still trying to get consular access to Gershkovich, which they have not been able to do.

He would not get into any specific conversations the U.S. is having with Russians about releasing Gershkovich or if a prisoner swap is a possibility.

"I just want to make a couple of things clear that is, the determination of wrongful detention, it doesn't start the clock necessarily on communicating with the Russians about getting him released," Kirby said. "We're very early in this process here and I certainly, I think you can understand why I wouldn't talk about any discussions we might be having with the Russians about his release or Paul [Whelan]'s release. We certainly wouldn't do that."

Kirby said the administration is "certainly having discussions about what we can do to get him released."

"I don't want to go into details about these internal deliberations, having things out in the public sphere viscerally might actually make it harder to get Evan and Paul home, and that's what we're focused on," Kirby said.

-ABC News' Justin Gomez