Mitchell Guist ‘Swamp People’ Star Dead

According to TMZ.com  - 10:19 AM PDT -- Law enforcement sources tell us ... Mitchell Guist of Swamp People  was out in his boat along the Belle River ... when he "fell." Witnesses say he appeared to have been suffering a seizure.

We're told another person on the boat returned to vessel to the dock and called 911. Emergency personnel responded to the scene and transported Mitchell to a nearby hospital ... but it was too late.