Rochester, MN (KROC-AM News) - A popular Rochesterfest event was marred by a tragedy Sunday morning.

The Rochester Fire Department says a competitor in the annual Rochesterfest Triathlon died during the swimming phase of the race. Deputy Fire Chief Steve Belau says 56-year-old Jeffrey Stevens of Rochester was swimming in Foster Arend Lake when another triathlete noticed him floundering in the water and tried to assist him. The second swimmer managed to keep the victim above water until a boat manned by emergency responders on patrol in the lake heard shouts for help and pulled the stricken racer on board.

He was not breathing, and after repeated efforts to revive were not successful, he was pronounced dead at the scene.

Belau says the Medical Examiner’s Office is investigating the cause of the man’s death. His name has not been released.