The city of Belgorod, which is close to the Ukrainian border, was unintentionally attacked, according to the Moscow defence ministry.
The explosion produced a massive hole in the middle of the city that was roughly 20 metres (60 feet) broad, according to regional governor Vyacheslav Gladkov.
According to him, numerous buildings were damaged, and two people suffered injuries.
According to the ministry, a Su-34 fighter-bomber jet unintentionally released aviation ordnance.
The incident took place at 22:15 local time (19:15 GMT) on Thursday, Russian news agencies said. An investigation is under way.
Photos and videos on social media show apartments damaged by the blast, while one image appears to a show a car on the roof of a building.
Belgorod – a city of 370,000 – is around 25 miles (40 km) from the Ukrainian border. It lies just north of Ukraine’s second city, Kharkiv, and people there have been living in fear of Ukrainian shelling since the Russian invasion of Ukraine last year.
Russian jets also regularly fly over the city on their way to Ukraine.