“…The addition of an armed security guard, however, drastically reduced the number of deaths. Similarly, in another study, the authors looked at how many off‐duty police officers would be needed to stop an active shooter in a stadium (Glass, Iyer, Lister‐Gruesbeck, Schulz, & Dietz, ). They found, through a computer simulation, that in a stadium of 4,000 people, 38 off‐duty police officers would be needed; in a stadium of 18,000, greater than 120 officers would be needed to reduce the casualties to three or less.…”