"A criminal investigation has been opened for an offense ... 'violation of rules of flights or preparations for them', after the catastrophe with the Mi-8 helicopter," the Russian Investigative Committee said in a statement.
Earlier in the day, the Mi-8 military helicopter made a hard landing in the Chukotka Autonomous Area in Russia's Far East, when it was conducting a training flight. Four people were killed, according to the Russian Defenсe Ministry.
Experts are currently studying the site of the incident, and expropriating pre-flight documentation and fuel samples, the committee added.
