Last Friday, Vince Neil was performing a the Monsters On The Mountain Festival in Tennessee. You can see Vince walking off to the right and at the very end of the video, he falls off the stage:
According to the Twitter user who posted the video, the bands finished out the song and continued with a Led Zeppelin cover. After, the bass player Dana Strum came out and stated:
"The truth is Vince fell and broke ribs when he fell. He can't breathe and he's gonna get dealt with medically."