Justin Bieber's management team can no longer book him concerts in venues without seats - for fear of leaving young fans seriously injured.
The pop superstar's rabid fanbase loses control at shows and standing-room-only arenas pose a big problem for his security team.
Bieber's bodyguard Kenneth Hamilton tells Rolling Stone magazine, "You've got a mob pushing, and even if it's little girls, they're crawling on top of each other with their arms and elbows, and getting injured."