(Street Life City News) Floyd “Money” Mayweather left the MGM Grand Garden Arena the victor in his bout against Marcos Maidana Saturday night, but according to reports numerous spectators left the event as victims of a stampede that broke out at the casino.

The Las Vegas Fire Department told Yahoo Sports that 20-40 people were injured from the melee that apparently began when fans tried to leave the arena through a small passageway. An estimated 300-400 people began rushing through the space causing others to be trampled.

The Las Vegas Sun reports an eyewitness said  “five or six” fights broke out with Metro Police, and another two security guards were hurt.

There were rumors that a gun being fired caused the massive rush to exit the venue, but investigators claim those reports cannot be corroborated. MGM is excepted to release a statement about the post-fight stampede today.

The story first broke as several observers posted about the incident on Twitter.

“Terrifying” crush according to fans. Rumors gun had been drawn but couldn’t find anyone who saw weapon. Tiny area for bulk of 15000 to pass

— Martin Rogers (@mrogersyahoo) May 4, 2014

Apparently there were people injured, trampled in an incident when folks were rushing from arena. #boxing #MayweatherMaidana

— Dan Rafael (@danrafaelespn) May 4, 2014

Eyewitness says fans trampled leaving Mayweather-Maidana fight tonight @ MGM Grand. “Like a herd of elephants running at us.” #vegas #fb

— Norm Clarke (@Norm_Clarke) May 4, 2014

wow they just broke down the barrier in the press room. All hell has broken loose

— Andreas Hale (@AndreasHale) May 4, 2014