You can also look at the statistics.
There are over 6 million CCW permits in the US. (states that allow concealed carry without a permit not included).
There are roughly 226 million adults (over 20) in the US. That means 3% of the adult population has a CCW.
If you have 200 people at an event, statistically you would have 6 people with a CCW. If one of them is packing and it shows, the media will get a shot of it.
Can you find any record of a person with a CCW or carrying openly at a function having committed a violent act?