Russia's St. Petersburg city came under a massive Ukrainian drone attack on Saturday, the city governor, Alexander Beglov, said on his Max channel, The Caspian Post reports, citing Xinhua.

"On the morning of June 6, St. Petersburg came under a large-scale attack by military unmanned aerial vehicles. Air defense systems are operating. In accordance with the recommendations of the Operational Command, I ask St. Petersburg residents to remain in their homes and not to go outside," the governor said.

Residents of St. Petersburg and the Leningrad region have been reporting hearing powerful sonic impacts resembling explosions since early Saturday morning.

According to the governor of the Leningrad region, which surrounds St. Petersburg, 86 UAVs had been shot down by Saturday morning.

No casualties or damage to infrastructure have been reported.

The attack marks the second major drone assault on St. Petersburg and the Leningrad region since the start of this year's St. Petersburg International Economic Forum, which concludes on Saturday.