A source close to the Air Force said the incident took place at the Luzhsky range near St. Petersburg on Saturday, Sept. 16. President Vladimir Putin visited the range on Monday.

A special commission comprising Defense Ministry and aviation industry officials was formed to ascertain the causes of the mishap and identify those responsible.

Kommersant says it was the third aviation accident in a week: a supersonic long-range bomber skidded off the runway on the day the Zapad 2017 drills kicked off on Sept. 14, and a training aircraft crashed two days later.