Russia denied involvement in a rocket attack that killed dozens of people at a train station in eastern Ukraine on Friday.

Kremlin spokesman Dmitry Peskov alleged that the involvement of Russian forces in the attack on the railway station in the Ukrainian city of Kramatorsk was already ruled out by the Russian Ministry of Defense, based on the type of missile that was used -- a Tochka-U short-range ballistic missile.

"Our Armed Forces do not use missiles of this type," Peskov told reporters during a press briefing Friday. "No combat tasks were set or planned for today in Kramatorsk."

The head of the European Commission, Ursula von der Leyen, and the bloc's top diplomat, Joseph Borrell, were due to arrive in Ukraine's capital on Friday.

While in Kyiv, the pair will meet with Ukrainian President Volodymyr Zelenskyy. It will be their first visit to the Ukrainian capital since Russia launched its invasion on Feb. 24.

At least 30 people were killed and more than 100 others injured in a rocket attack on a railway station in eastern Ukraine on Friday morning, authorities said.

According to Ukraine's state-owned railway company, two Russian rockets struck the train station in the city of Kramatorsk in Donetsk Oblast.

"This is a purposeful strike on the passenger infrastructure of the railway and the residents of the city of Kramatorsk," Ukrainian Railways said in a post on Facebook.

Donetsk Oblast Gov. Pavlo Kyrylenko said the station was teeming with civilians fleeing the Russian invasion. Kyrylenko accused Russian forces of wanting "to take as many peaceful people as possible."

"Thousands of people were at the station during the missile strike, as residents of Donetsk Oblast are being evacuated to safer regions of Ukraine," Kyrylenko said in a post on Telegram.

Ukrainian President Volodymyr Zelenskyy confirmed that "thousands of peaceful Ukrainians were waiting for evacuation" when the rockets hit the station.

"Not having the strength and courage to confront us on the battlefield, they are cynically destroying the civilian population," Zelenskyy said in a post on Facebook. "This is an evil that has no limits. And if it is not punished, it will never stop."

Graphic images provided by Ukrainian officials showed the aftermath of the attack -- bodies lying on the ground next to scattered luggage and debris, with charred vehicles parked nearby.

Russian forces in northern Ukraine have now fully withdrawn to neighboring Belarus and Russia, the U.K. Ministry of Defense said Friday in an intelligence update.

"At least some of these forces will be transferred to East Ukraine to fight in the Donbas," the ministry added. "Many of these forces will require significant replenishment before being ready to deploy further east with any mass redeployment from the north likely to take at least a week minimum."

Meanwhile, cities in eastern and southern Ukraine continue to be shelled by Russian forces as the troops advance "further south from the strategically important city of Izium which remains under their control," according to the ministry.

The State Department has still not confirmed reports that two former U.S. service members who volunteered to help Ukrainian forces have gone missing, spokesperson Ned Price said Thursday.

The Americans, Andy Tai Ngoc Huynh and Alexander Drueke, are both from Alabama.

"We are limited in terms of what we know at the moment," Price said. "We're closely monitoring the situation we are in contact with Ukrainian authorities, as well as with the International Committee of the Red Cross, and the families of the two reported missing U.S. citizens."

The department has not "seen anything from the Russians indicating that two such individuals are in their custody," Price said.

"If the Russians were to claim that they had such individuals, I assume we would pursue that. If we had reason to believe -- credible reasons to believe -- that these individuals were in Russian custody, we would pursue that as appropriate," Price continued.

Price was asked whether the department was tracking any other cases of Americans purportedly captured on the battlefield, and he said the department was aware of reports about "one additional American whose whereabouts are unknown.”

"Similarly, our understanding was that this individual had traveled to Ukraine to take up arms," Price said. He said the person was identified as missing "in recent weeks" and that the State Department was also in contact with their family.

Alabama Rep. Terri Sewell said that Drueke’s mother reached out to her office after losing contact with him. Sewell is helping the family locate him. Alabama Rep. Robert Aderholt said his office is helping in the search for Huynh after his family reached out to the congressman's office this week.

-ABC News' Shannon Crawford