Arm the security officers with pressurized cans of blue dye. Spray the crowd, and follow those who exit and arrest them. You won’t get them all, but it can be seen who was in the crowd.
As long as there are some serious methods of crowd control here, can I suggest pressurized cans of the slickest substances sprayed on the floors. That would break a few noggins and slow the crowd down. It can’t be stopped anyway, so just slow them down and see who has a head booboo. But Shirley, I jest.