Unknown persons in the correspondence promised them a reward of $20,000.
This is the second incident with schoolchildren in 2 weeks. Last time, the Mi-8 was burned at the Noyabrsk airport in the Yamalo-Nenets Autonomous District on September 11.
If this is the same Mi-8 sabotage by kids from a week or so ago, this was the second espionage they did. The first paid them a couple hundred dollars. The kids were caught on this one, and both sustained serious burns (which is how they were caught at the hospital).