Russia is witnessing a series of attempts to deliberately start fires.. What is happening?

Russia has witnessed a series of attempts to deliberately set fires targeting banks, shopping centres, post offices and government buildings over the past three days, according to media.
About 20 incidents of individuals separately trying to detonate small explosive devices or throw fireworks at buildings have been recorded since Friday, especially in Moscow, St. Petersburg and their suburbs, according to the TASS news agency and the independent website Fontanka.
TASS quoted an unidentified police source as saying that fraudsters recruited these people via the Internet to carry out these attacks in exchange for money.

Russian security services

Pictures taken by surveillance cameras in some locations, and circulated on social media, showed people filming with their mobile phones the fires they were trying to start.
Footage showed an ATM machine and nearby windows shattered after an attack, while another video clip showed a police car on fire.
Russian security services have warned that Ukrainian scammers are calling elderly people to ask them to deliberately set fires in exchange for money or access to blocked accounts.