Russian missiles struck a city in central Ukraine on Thursday, killing at least 23 people and wounding more than 100 others far from the front lines, Ukrainian authorities said. Ukraine's president accused Russia of deliberately targeting civilians in locations without military value.

Officials said Kalibr cruise missiles fired from a Russian ship in the Black Sea damaged a medical clinic, offices, stores and residential buildings in Vinnytsia, a city 268 kilometers (167 miles) southwest of the capital, Kyiv. Vinnytsia region Gov. Serhiy Borzov said Ukrainian air defenses downed two of the four incoming Russian missiles.

National Police Chief Ihor Klymenko said only six bodies had been identified so far, while 39 people were still missing. Three children younger than 10 where among the dead. Of the 66 people hospitalized, five remained in critical condition while 34 sustained severe injuries, Ukraine’s State Emergency Service said.

“It was a building of a medical organization. When the first rocket hit it, glass fell from my windows," said Vinnytsia resident Svitlana Kubas, 74. “And when the second wave came, it was so deafening that my head is still buzzing. It tore out the very outermost door, tore it right through the holes.”

Borzov said 36 apartment buildings were damaged and residents have been evacuated. Along with hitting buildings, the missiles ignited a fire that spread to 50 cars in a parking lot, officials said.

“These are quite high-precision missiles. ... They knew where they were hitting,” Borzov told the AP.

Russia denied targeting civilians.

Also read: Minister: Ukraine needs assurances to resume grain exports

“Russia only strikes at military targets in Ukraine. The strike on Vinnytsia targeted an officers’ residence, where preparations by Ukrainian armed forces were underway,” Evgeny Varganov, a member of Russia’s permanent U.N. mission, said in an address to the chamber.

Among the buildings damaged in the strike was the House of Officers, a Soviet-era concert hall.

Margarita Simonyan, head of the state-controlled Russian television network RT, said on her messaging app channel that military officials told her a building in Vinnytsia was targeted because it housed Ukrainian “Nazis.”

Ukrainian President Volodymyr Zelenskyy repeated his call for Russia to be declared a state sponsor of terrorism. The strike happened as government officials from about 40 countries met in The Hague, Netherlands, to discuss coordinating investigations and prosecutions of potential war crimes committed in Ukraine.

“No other country in the world represents such a terrorist threat as Russia,” Zelenskyy said in his nightly video address. “No other country in the world allows itself every day to use cruise missiles and rocket artillery to destroy cities and ordinary human life."

Zelenskyy said that among those killed was a 4-year-old girl named Liza, whose mother was badly wounded. A video of the little girl, twirling in a lavender dress in a field of lavender, was widely shared on social media.

“Today, our hearts are bleeding, and our eyes are full of tears because our family of many thousands has lost one of our own,” the charity Down Syndrome wrote. It said: “They were just on their way from a speech therapy class, and they just happened to be in the wrong place at the wrong time."

Zelenskyy's wife later posted that she had met this “wonderful girl” while filming a Christmas video with a group of children, who were given oversized ornaments to paint.

Also read: Ukraine reports striking Russian ammunition depot in south

“The little mischievous girl then managed in a half an hour to paint not only herself, her holiday dress, but also all the other children, me, the cameramen and the director ... Look at her alive, please,” Olena Zelenska wrote in a note accompanying the video.

Zelenskyy called for creating a mechanism for confiscating Russian assets around the world and using them to compensate the victims of “Russian terror.”

Ukrainian Interior Minister Denys Monastyrsky echoed Zelenskyy, calling the missile attack a “war crime" intended to intimidate Ukrainians while the country's forces hold out in the east.

He said several dozen people were detained for questioning on suspicion that the Russian forces had received targeting assistance from someone on the ground.

The U.S. Embassy in Kyiv issued a security alert late Thursday urging all U.S. citizens remaining in Ukraine to leave immediately. The alert, which appeared to be in response to the Vinnytsia attack, asserted that large gatherings and organized events “may serve as Russian military targets anywhere in Ukraine, including its western regions.”

Vinnytsia is one of Ukraine's largest cities, with a prewar population of 370,000. Thousands of people from eastern Ukraine, where Russia has concentrated its offensive, have fled there since Russia invaded Ukraine on Feb. 24.

Kateryna Popova said she saw many injured people lying on the street after the missiles struck. Popova had fled from Kharkiv in March in search of safety in “quiet” Vinnytsia. But the missile attack changed all that.

“We did not expect this. Now we feel like we don’t have a home again,” she said.

Ukrainian military analyst Oleh Zhdanov said the attack mirrors previous ones on residential areas that Moscow has launched “to try to pressure Kyiv to make some concessions.”

"Russia has used the same tactics when it hit the Odesa region, Kremenchuk, Chasiv Yar and other areas," Zhdanov said. “The Kremlin wants to show that it will keep using unconventional methods of war and kill civilians in defiance of Kyiv and the entire international community.”

Before the missiles hit Vinnytsia, the president’s office reported the deaths of five civilians and the wounding of eight more in Russian attacks over the past day. One person was wounded when a missile damaged several buildings in the southern city of Mykolaiv early Thursday. A missile attack on Wednesday killed at least five people in the city.

Russian forces also continued artillery and missile attacks in eastern Ukraine, primarily in the Donetsk region after overtaking the adjacent Luhansk region. The two regions make up the Donbas, a mostly Russian-speaking area of steel factories, mines and other industries that powered Ukraine's economy.

Donetsk Gov. Pavlo Kyrylenko, meanwhile, urged residents to evacuate as “quickly as possible.”

“We are urging civilians to leave the region, where electricity, water and gas are in short supply after the Russian shelling,” Kyrylenko said in televised remarks. “The fighting is intensifying, and people should stop risking their lives and leave the region.”

On the battlefront, Russian and Ukrainian militaries are seeking to replenish their depleted stocks of unmanned aerial vehicles to pinpoint enemy positions and guide artillery strikes.

Both sides are looking to procure jamming-resistant, advanced drones that could offer a decisive edge in battle. Ukrainian officials say the demand for such technology is “immense” with crowdfunding efforts underway to raise the necessary cash.