According to reports, an explosion occurred in an apartment in St. Petersburg, injuring six people.

The city’s governor, Alexander Beglov, said “an incident” occurred in the northeastern region of Krasnovardysky.

The cause of the incident was unclear, but Berglov said residents had been evacuated from their homes and there were no casualties.

Russian media claimed that the incident may have been caused by a downed Ukrainian drone that was flying to a nearby fuel depot.

The explosion in the early hours of Saturday left six people in need of medical help, RIA Novosti said.

The outlet also reportedly released a video showing the moment the apartment building was attacked. Video showed an intense flash of light engulfing the side of the building, sending shards of debris flying into the air.

Another video shows a car alarm going off.

The claims have not been confirmed, and the Ukrainian and Russian defense ministries have yet to comment on the incident.