A CNN employee found sensitive national security planning documents in the seat-back pocket of a commercial plane, the network reported Monday.

The documents, which concerned the national security response to an exercise simulating a biological attack on the Super Bowl, were found weeks ago.

CNN kept them under wraps until after the game at the request of the Department of Homeland Security, which cited national security concerns. A spokesperson for DHS told CNN that “[t]his exercise was a resounding success and was not conducted in response to any specific, credible threat of a bioterrorism attack.”

The documents contained mixed reviews of the exercise, CNN reported, including that there were “differences of opinion” over how many people had been exposed to the simulated biological attack, “which led to differences of opinion on courses of action.”

Local health agencies, according to the documents, also expressed confusion over the meaning of the alerts about the simulated attack, and how widely the alerts could be shared. That, the documents said “creates a situation where local officials are deciding on courses of action from limited points of view.”

A travel itinerary and boarding pass belonging to Michael V. Walter accompanied the documents, CNN said. Walter is the program manager of BioWatch, which DHS says aims to provide early detection of airborne biological attacks.

Watch CNN’s report about the documents below, or read it here.

