(CNN) At least 21 people, including a child, were killed when Russia launched overnight missile strikes at a residential building and a recreation center near Odesa, southern Ukraine, officials said on Friday.
The attack hit a housing block, killing 16 people, according to Ukraine's State Emergency Services.
Another four people, including a child, died when a missile hit a community center, while a third missile landed in a field. At least 40 people were injured, responders said.
"We don't expect to find anyone alive, but there is a chance," first deputy interior minister Yevhenii Yenin said on Friday, speaking from the scene of the attacks.
Images from the scene showed the residential building torn apart and debris strewn across the ground.
Ukrainian President Volodymyr Zelensky said Russia is conducting terrorism against his country's cities and people.
"This is not a single strike and not an accident, as the Russian mass media say every day. This is a targeted Russian missile attack, Russian terror against our cities, towns, our people -- adults and children," he said during a meeting with Norwegian Prime Minister Jonas Gahr Støre in Kyiv.
He described the Russian missile as a "supersonic cruise anti-ship missile" that was "created to attack aircraft carriers and other large military ships, and the Russian army used it against an ordinary building with ordinary civilians."
Ukraine's Foreign Minister Dmytro Kuleba condemned the strikes on Twitter, saying: "Terrorist state Russia continues its war against civilians with overnight missile strikes on Odesa region killing dozens, including children. I urge partners to provide Ukraine with modern missile defense systems as soon as possible. Help us save lives and put an end to this war."
One of the buildings struck by the strikes was a rehabilitation center for treating Moldovan children with health problems, according to Moldova's Minister of Health Ala Nemerenco.
In a statement on Facebook, Nemerenco said that although the building itself was not badly damaged, one employee was killed and five were injured in the attack.
The renovated sanatorium gave "children with health problems in the Republic of Moldova the opportunity to benefit from medical rehabilitation services on the Black Sea coast," Nemerenco said.
She paid tribute to the facilities' medical staff who were injured and killed in the Russian bombardment.
"These peaceful people made the days of Moldova's children more beautiful; they took care of their rehabilitation with a lot of love and dedication, and we wish them from the bottom of our hearts a total recovery. To the family of the deceased colleague, we express our deepest condolences and sorrow."
The Moldovan-owned rehabilitation center had been closed to patients since the start of the coronavirus pandemic, said Nemerenco. No children are thought to have been at the center at the time of the attack.
Fighting has raged across the Odesa region, which borders the strategically significant Black Sea, for several weeks.
But some Ukrainian officials are cautiously optimistic that the regaining of Snake Island, a Ukrainian outpost on the Black Sea, could mean a reduction of shelling toward Odesa.
"It's now known why the enemy took (Snake) island. They filled the territory with the means of destruction and fired from them," state border service spokesman Andrii Demchenko said at a briefing Friday. "We hope now shelling of the territory of Ukraine will decrease."
Kremlin spokesman Dmitry Peskov denied Friday that Russia targets civilian areas in Ukraine and repeated the frequent claim that it focuses its air strikes on buildings containing ammunition or training troops. But as with previous such claims after Russian attacks, he failed to provide any evidence that this was the case.
Russia has made some slow but significant gains in the east of Ukraine since refocusing its invasion there. An official in the Russian-backed Luhansk People's Republic said on Friday that Russian troops have "completely taken over" an oil refinery in the embattled city of Lysychansk, eastern Ukraine, though Ukraine admitted only to a "partial" Russian success.
The Russian barrage on Lysychansk has been relentless, according to Serhii Hayday, head of the Luhansk region military administration.
"People dream of at least half an hour of silence, but the occupiers do not stop firing from all available weapons," Hayday said on Thursday.