This is one of the many reasons concerts have so much security these days. Motley Crue were playing a gig when a fan rushed the stage knocking Mick Mars to the ground, then tackling Vince Neil.

With Mick's bone disease he could have easily been hurt pretty badly but fortunately he was OK. You can even see Nikki Sixx kicking the guy while security had him down on the stage. Personally I think that's one of the times its ok to kick a guy when he's down. What a douce.