A Ukrainian missile strike Friday on the Russian-controlled city of Lugansk ripped through a block of flats, killing four people and wounding over 40, Russia-appointed officials said.
The eastern Lugansk border region is almost entirely under the control of Moscow, which has claimed its full annexation.
The main city, also called Lugansk, came under a "massive" missile attack on Friday morning, according to its Russia-appointed head, Leonid Pasechnik.
A section of an apartment block collapsed and the "bodies of four peaceful civilians killed were removed from the rubble", the Moscow-backed region's government said on Telegram.
"Forty-six people have received medical treatment," said regional health minister Nataliya Pashchenko, adding that they included an eight-year-old boy and three teenage boys.
The condition of ten of the injured is "grave" she said.
The strike tore open the facade of a five-storey Soviet-era block of flats from the roof down and left a deep crater in the ground, images posted by the Russian emergency services showed.
Rescuers carried out one elderly casualty on a stretcher, footage posted by the emergency services showed.
"Ukrainian nationalists in the daytime launched a massive attack on civilian infrastructure of Lugansk," Pasechnik said on Telegram.
"In one multi-storey block, a section has entirely collapsed. There are people under the ruins. Rescuers are working to free them," he said.
The strike damaged a total of 33 blocks of flats in the east of the city as well as two schools, three kindergartens and a higher education college, Pasechnik said.
The Russian defence ministry accused Ukraine of targeting civilian areas, saying "the Kyiv regime... deliberately fired five US-made ATACMS missiles at residential districts of the city of Lugansk".
"Four American missiles were shot down by Russian air defences. One missile struck two blocks of flats," the ministry said.
The attack came as Russia's defence ministry claimed new advances against Kyiv's stretched military.
Over the last week, Russian troops "improved their positions along the front line and liberated the settlement of Paraskoviivka", the ministry said.
The village is around 25 kilometres (15 miles) southwest of the city of Donetsk, capital of the region that Moscow claims to have annexed in 2022.
After months of stalemate, Moscow is gaining ground in the east, capturing 47 Ukrainian towns and villages in total since the start of this year, according to President Vladimir Putin.
"Since the beginning of this year alone, 47, I think, settlements have been liberated," Putin told attendees at the Saint Petersburg International Economic Forum.
In the central city of Nikopol in the Dnipropetrovsk region, Russian shelling killed a 71-year-old woman, the regional authorities said.
The city is on the Dnipro River and Russian forces control the opposite bank.
