Russia is blaming the Ukrainian strike after an explosion in Belgorod caused an entire block of flats to collapse.
CCTV from the scene showed a huge explosion at the base of the 10-storey structure and then the building collapsing.
At least 19 people were injured and there were reports of deaths and people trapped in the rubble.
The Russian city is close to the border with Kharkiv, Ukraine, where Moscow’s troops launched an offensive on Friday.
The Belgorod region has been frequently targeted by Ukrainian forces since the start of Russia’s full-scale invasion of Ukraine in 2022, but there has been no word from Kiev on the latest incident.
Ukrainian officials have previously said the cross-border attacks, including in Belgorod, did not target civilians.
‘He could not escape’
But the regional governor of Belgorod, Vyacheslav Kladkov, described the Ukrainian shell as the cause of the bombing.
Images from the scene show rescuers manually clearing debris as they search for survivors. Surrounding residences have been evacuated amid fears the main building could collapse further.
A resident told Russian state news agency RIA Novosti that her husband was in a bedroom in the building when the blast occurred and suffered head and facial injuries. “He has no time,” she said, to escape.
A spokesman for Russia’s intelligence agency said a criminal case had been opened.
The incident comes as fighting continues across the border in north-eastern Ukraine, where Russian forces have infiltrated the Kharkiv region.
The Defense Ministry in Moscow says its forces have captured several villages there, while Kyiv says it is launching counterattacks.
