A Russian-guided aerial bomb hit a blood transfusion centre in the town of Kupiansk, in the eastern Kharkiv region late on Saturday, Ukrainian President Volodymyr Zelensky said.
“There are dead and wounded,” he said on his Telegram channel.
“Rescuers are extinguishing the fire. This war crime alone says everything about Russian aggression.”
Kupiansk is a railway hub fewer than 10 miles from the front and a couple dozen miles from the Russian border.
The strike came shortly after Mr Zelensky said Russian missiles had hit a facility of the Ukrainian aeronautics group Motor Sich, a maker of plane and helicopter engines and other components.
It is one of several companies requisitioned by the government since Moscow’s invasion. The Motor Sich site is near Khmelnytskyi in western Ukraine, around 190 miles southwest of Kyiv.
The region, home to a major Ukrainian airbase, has been regularly targeted by Russian strikes in recent months.
Both attacks came just hours after Kyiv hit a Russian tanker in the Kerch Strait.
In his evening address, Mr Zelensky remained defiant, insisting that “no matter how many such Russian attacks there are, they will still do nothing for the enemy”.
Meanwhile on the front line, Russia said on Saturday it had captured the settlement of Novoselivske in northeastern Ukraine, where Kyiv said it was confronted with a growing number of attacks.
Footage from the Russian army showed Novoselivske completely destroyed, with white smoke billowing over crumbling buildings.
Ukrainian army spokeswoman Ganna Malyar said that Russian troops were aiming to draw Ukrainian resources to the east, as Ukraine pursues its counter-offensive in the south.