At least three people have died in explosions in the Russian city of Belgorod, near the border with Ukraine, said regional governor Vyacheslav Gladkov.
The blasts partially destroyed 11 apartment buildings and at least 39 private residential buildings, he said.
Air defence systems were activated by the blasts, he added.
The governor’s statement could not be independently confirmed and there was no immediate reaction from Ukraine.
The information came from Mr Gladkov’s channel on the Telegram social media app.
Since Russia invaded on 24 February, claiming it wanted to “demilitarise” and “de-Nazify” Ukraine after it moved closer to Nato, thousands of civilians and combatants have been killed or wounded, while at least 12 million people have fled their homes.
Western states have responded by arming Ukraine and placing unprecedented sanctions on Russia, a nuclear superpower and global energy supplier.