It was the Ukraine not Russia
31-year-old Douglas Dedge was an American mixed martial artist who was the first known American competitor to be fatally injured in an MMA fight and the first death in the modern era of MMA. On March 16, 1998 Dedge competed at an unsanctioned "World Super Challenge" event in Kiev, Ukraine. After tapping out to strikes, Dedge stood and almost immediately collapsed back to the mat. Dedge was then taken to the Kiev Institute of Surgery where he died two days later on March 18 of what the chief emergency room doctor termed "severe brain injuries".
Dedge was reported to have passed out during a training session leading up to the bout and it is now widely believed (though never officially confirmed) that Dedge had a preexisting medical condition.
After doing a search there have been a few deaths... according to wiki anyway