All of the victims were civilians and a 6-year-old boy was among those killed.
KYIV and LONDON -- At least 51 people, including a child, were killed Thursday in a Russian missile strike on a village in the Kharkiv region of eastern Ukraine, officials said.
A 6-year-old boy was among those killed in the attack, which targeted a building that housed a cafe and a shop in the village of Groza in the Kupyansk district. Six others were wounded and all of the casualties were civilians, according to the Kharkiv Regional Prosecutor's Office
A memorial service for a slain Ukrainian soldier was taking place in the cafe when the missile struck. Only civilians were attending the event, the regional prosecutor's office told ABC News.
Preliminary information suggests an Iskander missile was used by Russian forces in the attack, according to Ukrainian Interior Minister Igor Klymenko.
It's the deadliest strike to occur in the Kharkiv region since the start of Russia's invasion, according to the local government. It's also one of the deadliest attacks to take place in all of Ukraine in recent months.
Russian troops launched a full-scale invasion of neighboring Ukraine in February 2022. In June of this year, Ukrainian forces launched a counteroffensive in an effort to reclaim occupied territory.
Ukrainian President Volodymyr Zelenskyy denounced Thursday's attack as a "demonstrably brutal Russian crime" and "a completely deliberate act of terrorism." He urged Western allies to help strengthen Ukraine's air defenses, saying that "Russian terror must be stopped."
"Russia needs this and similar terrorist attacks for only one thing: to make its genocidal aggression the new norm for the whole world," Zelenskyy said Thursday. "Now we are talking with European leaders, in particular, about strengthening our air defense, strengthening our soldiers, giving our country protection from terror. And we will respond to the terrorists."
Earlier on Thursday, Zelenskyy asked more than 40 European leaders gathered in Spain for their continued assistance and more weapons to help his country fight against Russian aggression.
In an emotional speech before the European Political Community Summit in Granada, Zelenskyy said schoolchildren in eastern Ukraine's Kharkiv region were having to learn remotely or attend classes underground in subway stations due to air raids.
"Until there is a fully effective air defense system, children cannot attend school," the Ukrainian president said Thursday, warning that "there will be a lot of Russian attacks in [the] winter."
Last winter, Russian missiles and drones targeted Ukraine's energy system and other vital infrastructure, causing continuous power outages across the eastern European country.
Zelenskyy confirmed that Spain has agreed to provide Ukraine with air defense capabilities in a new aid package.
The Ukrainian president also voiced confidence in continued support from the United States, despite what he called a "political storm" in Washington, D.C., after aid for Ukraine did not make the cut for a last-minute deal by American lawmakers to avoid a government shutdown.
"I am confident in America," he said. "They are strong people with strong institutions and a strong democracy."
Zelenskyy warned that one of the scenarios Russia is considering in the conflict is to freeze the war until 2028 to replenish its reserves. He said Russian President Vladimir Putin should not be allowed to beef up his military or else Russia could attack beyond Ukraine by 2028.
"Let only Putin's ambitions be a ruin, not our countries, not our cities," Zelenskyy said. "Children of every country deserve to be safe. Everywhere in the country, not just in the subway, not just in underground shelters, but everywhere. We must make it possible. We must ensure that Ukraine wins."