A Russian Sukhoi-34 supersonic warplane accidentally fired a weapon into the city of Belgorod near Ukraine late on Thursday, causing an explosion and injuring three people.

Video footage from the site showed piles of concrete on the street, several damaged cars and a building with broken windows. One shot showed what appeared to be car upside down on the roof of a store.

Belgorod region governor Vyacheslav Gladkov announced a state of emergency overnight and said there was a crater measuring 20 metres (65 feet) across on one of the main streets. Four cars and four apartment buildings were damaged, he added.

Three people had been injured, he said.

"Thank God there are no dead," Vyacheslav Gladkov said in a statement on Telegram, adding that an apartment building had been evacuated overnight.

Tass cited the Russian defence ministry as saying that a Su-34 supersonic fighter-bomber jet had accidentally discharged a munition.

"As a Sukhoi Su-34 air force plane was flying over the city of Belgorod there was an accidental discharge of aviation ammunition," Tass cited the defence ministry as saying.

It did not say what kind of weapon was involved.

The ministry said some buildings had been damaged and announced a probe was already under way, according to Tass.

The Belgorod region is one of several parts of southern Russia where targets such as fuel and ammunition stores have been rocked by explosions since the start of what Moscow calls its "special military operation" in Ukraine on Feb. 24, 2022. (Reporting by David Ljunggren and Guy Faulconbridge; editing by Jonathan Oatis, Jamie Freed and Christina Fincher)