The defence ministry in Moscow says a Russian fighter jet accidentally bombed the city of Belgorod near the border with Ukraine.
Regional Governor Vyacheslav Gladkov said the blast had left a huge crater about 20 metres (60 ft) wide in the city centre.
Two women were injured and several buildings were damaged, he said.
A Su-34 fighter-bomber jet accidentally discharged aircraft ordnance, the ministry said.
(BBC)