The defence ministry successful Moscow says a Russian combatant pitchy accidentally fired its ammunition into the metropolis of Belgorod adjacent the borderline with Ukraine.
Regional Governor Vyacheslav Gladkov said the blast had near a immense crater astir 20 metres (60 ft) wide successful the metropolis centre.
Two women were injured and respective buildings were damaged, helium said.
A Su-34 fighter-bomber pitchy accidentally discharged aviation ammunition, the ministry said.
The incidental took spot astatine 22:15 section clip (19:15 GMT) connected Thursday, Russian quality agencies said. An probe is nether way.
Photos and videos connected societal media amusement apartments damaged by the blast, portion 1 representation appears to a amusement a car connected the extortion of a building.
Belgorod - a metropolis of 370,000 - is astir 25 miles (40 km) from the Ukrainian border. It lies conscionable northbound of Ukraine's 2nd city, Kharkiv, and has been often shelled since the Russian penetration of Ukraine.
Russian jets besides regularly alert implicit the metropolis connected their mode to Ukraine.