Russia is blaming a Ukrainian strike after an entire section of an apartment building collapsed following an explosion in Belgorod.
CCTV from the scene shows a large blast near the base of the 10-storey block and then the building falling in.
The regional governor said two bodies had been pulled from the rubble.
At least 19 people are believed to have been injured.
The Russian city is near the border with Kharkiv in Ukraine, where Moscow’s troops launched an offensive on Friday.
The Belgorod region has often been targeted by Ukrainian forces since the start of Russia’s full-scale invasion of Ukraine in 2022.
The incident comes as “intense battles” continue just across the border in north-eastern Ukraine, where Russian forces have made gains in recent days
In his evening address on Sunday, Ukrainian President Volodymyr Zelensky said the Russian offensive had displaced thousands.