We've already seen this with the Olympics. Security costs are one of the biggest reasons why many cities have withdrawn their Olympic bids in recent years.
“Security costs are likely to drive a lot of large-crowd events out of business”............
I question if the “security” folks would have caught this shooter prior to his act. Lots of “unknowns” about this tragic and horrible act. Prayers for all who lost their lives, their families and those wounded. TERRIBLE!