CBS Chicago:

(CBS) — It was stunning for those who watched Thursday night as federal agents investigated a possible nuclear threat at Chicago’s Ogilvie Transportation Center.

CBS 2′s photojournalist Lana Hinshaw-Klann happened to be at the scene and used a cell-phone camera to record agents in action. Reporter Dave Savini looks into what agents were looking for and what they found.

Sources say the agents were members of the elite TSA VIPR team on the 5:04pm Union Pacific West line. They were carrying hand-held nuclear-detection devices that picked up a reading.

Turns out someone took a nuclear stress test — whatever the hell that is.