David Guetta Gang Stabbings at Big Vegas Show

9/20/2015 1:00 AM PDT
EXCLUSIVE

According to police docs, the stabbing went down at 7 AM on Labor Day ... which means it happened during the tail end of David Guetta's show. Skrillex and Diplo did not perform at XS until later that evening.A violent fight was swept under the rug in Vegas over Labor Day, when 4 people were seriously stabbed night during a DJ's show at XS Nightclub.

Law enforcement tells TMZ, a huge fight involving around 20 people broke out in the middle of the show, leaving 4 with stab wounds. Our sources say it has all the markings of a gang fight. 

We're told the injuries were serious including a punctured lung and spleen but everyone survived -- one victim admitted to gang ties and didn't want to go forward with any charges.

However, law enforcement tells us they have arrested someone on 3 counts of attempted murder. That said, cops are having problems developing the case, because almost everyone they've tried to interview developed a case of amnesia.