Ukraine's President Volodymyr Zelenskyy condemned Moscow for "waging war on hospitals" after Russian strikes on a hospital in the border city of Sumy killed 10 people Saturday.
Ukrainian Interior Minister Igor Klymenko wrote on Telegram that the first strike "killed one person" and damaged several floors of the hospital.
"During the evacuation of patients, the enemy struck again," he added.
Sumy lies just across the border from Russia's Kursk region, where Kyiv launched a surprise offensive on August 6, aimed in part at creating a "buffer zone" inside Russia.
"Russia hit one of the city's hospitals with Shahed drones," Zelenskyy wrote on Telegram.
The attack hit the St Panteleimon Clinical Hospital near the city centre, officials said, with a nurse among the dead.
The attack comes as Zelenskyy is pressing Kyiv's Western allies to allow the use of long-range precision weapons to strike deep inside Russia.
"Everyone in the world who speaks about this war must pay attention to what Russia is targeting. They are waging war on hospitals, civilian facilities and people's lives," the president said.
Ukrainian Prime Minister Denys Shmygal said the attack was "more evidence of Russia's war crimes."
Zelenskyy posted photos of smoke pouring from windows above the destroyed entrance to the hospital, rescuers carrying patients down the stairs and treating two policemen lying on the ground.
On Saturday morning, three drones attacked the regional capital city and two hit the hospital, Ukraine's air force said.
A first strike was followed by another around an hour later on Saturday morning, officials said, apparently targeting the rescue operation to maximize casualties.
Russia has destroyed or damaged at least 1,736 medical facilities in Ukraine since its February 2022 invasion, Human Rights Watch reported in July.
These have included a children's hospital in Kyiv in July and a maternity hospital in Mariupol in March 2022.
Regional prosecutors said the first attack took place at around 7:35 am and the second about an hour later.
Images posted by officials showed body bags lying on the pavement outside the four-story building with a destroyed entrance and the roof partially ripped off.
The hospital's director Volodymyr Potseluyev told Suspilne media outlet that the hospital's admission department, casualty department, and fourth floor were destroyed.
He said seriously injured patients had been transferred to intensive care units at other hospitals.
Regional authorities said the strikes also hit a residential area and posted images of flats with broken windows.
Dobrobat, a volunteer group that helps repair damaged homes, wrote on Facebook that its volunteers were working at the scene when the second strike came.
It posted a video showing thick smoke, explosions, and people rushing to take shelter as sirens wailed.
"People are just lying on the street dead," a volunteer said, filming himself on his phone.
Ukraine's air force reported shooting down 68 Russian attack drones out of 73 in multiple regions overnight, including Sumy, and two out of four cruise missiles launched overnight by Russia.
In the central city of Kryvyi Rig, rescuers pulled another body from the rubble of a police office building struck by a missile on Friday, regional governor Sergiy Lysak said, taking the toll to four.
A drone strike in a border village in the eastern Kharkiv region killed one man and wounding three women, regional governor Oleg Synegubov said.
In Russia's Belgorod border region, governor Vyacheslav Gladkov said a local resident was killed Saturday morning by a drone attack.
Closing his visit to the United States, Zelensky released a statement later Saturday thanking US President Joe Biden for the latest military aid package of $8 billion, and the US Congress for its "unwavering" support.
Russian Foreign Minister Sergei Lavrov warned European countries against seeking confrontation with Moscow in a speech to the UN General Assembly in New York.
Western countries "hope to defeat Russia using the illegitimate neo-Nazi Kyiv regime, but they're already preparing Europe for it to also throw itself into this suicidal escapade," he said.
"I'm not going to talk here about the senselessness and the danger of the very idea of trying to fight to victory with a nuclear power."