In Saratov and Engels, schools canceled classes after an industrial facility was damaged in a UAV attack.
The regional governor, Roman Busargin, instructed local authorities to urgently notify parents about switching schoolchildren to remote learning.
The governor did not specify which facility was attacked.
Local social media channels claim that at least 11 unmanned aerial vehicles hit an oil depot in Engels.
As reported, a week earlier, a UAV attack on an oil depot in Engels destroyed or damaged nine fuel storage tanks, each with a capacity of 120,000 cubic meters.