"At first security guards thought patrons were trying to leave without paying and blocked exits, trapping victims inside." One other thing to improve is to have

"At first security guards thought patrons were trying to leave without paying and blocked exits, trapping victims inside." One other thing to improve is to have people pay up front. This would have prevented the guards from closing the exits. If you have a tab apparently sometimes people try to do a mass break out. Another great thing is to always have people leave through the fire exits to get them familiar with them (I think they do this in the UK).