A man by the name of Alonzo Rodriguez sent at least one threatening text message to a friend, which have since become public, describing a potential shooting at an anime convention...
ATTENTION: To everyone attending #AX2018 please be cautious this individual has made threats of a potential shooting at Anime Expo, this individual was also a volunteer staff member at Ronin-Expo and was asked to leave after making other Staff Members feel uncomfortable, also supposedly this individual also brought a knife to Anime Conji, a convention in San Diego, and "put the staff under duress" during the event. If you happen to see this individual please notify the authorities immediately and do NOT approach him.
Anime Expo is aware of the incident and are working with security teams and local law enforcement to ensure a safe and fun event.
https://twitter.com/AnimeExpo/status/1005588596122791936