A large-scale Ukrainian drone attack on Russia triggered an earthquake-sized blast at a major arsenal in the Tver region on Wednesday, forcing the evacuation of a nearby town, war bloggers and some media reported.
Unverified video and images on social media showed a huge ball of flame blasting high into the night sky and multiple detonations thundering across a lake about 380 km (240 miles) west of Moscow.
NASA satellites picked up intense heat sources emanating from an area of about 14 square kilometres (5 square miles) at the site in the early hours and earthquake monitoring stations picked up what sensors thought was a small earthquake in the area.
Russian state media have in the past reported that a major arsenal for conventional weapons was located at the site of the blasts. State media, which is now subject to military censorship laws, was muted in its reporting on Wednesday.
Igor Rudenya, the governor of the Tver region, said that Ukrainian drones had been shot down, that a fire had broken out and that some residents were being evacuated. He did not say what was burning.
A source in Ukraine's SBU state security service told Reuters the drone attack destroyed a warehouse storing missiles, guided bombs and artillery ammunition. There was no immediate comment from the Ukrainian government.
Russia and Ukraine each reported dozens of enemy drone attacks on their territory overnight, with Russian forces advancing in eastern Ukraine.