It was a known actor to the local police so it could have happened at any conference, really.

It was someone called in “a suspicious backpack with wires” which is absolutely hilarious at DEF CON

Hah...that could easily have been MY backpack.

When I'm at DEFCON, I bring a fun little device. It's an ESP8266 that constantly listens for WiFi probes coming from people's mobile devices. It then displays the SSID (the network name) on a scrolling LED text display. I keep it plugged into one of those Anker battery banks. 10,000 mAh will power it for ~16 hours, so it lasts the entire day.