It sounds like people were making independent reports, it's not like they were all listening to a "War of the Worlds" broadcast and then reporting based on what they heard on the radio.

Can it really be called "mass hysteria" if the individuals didn't know about each other's reports?

From the original description:

On Friday, Myers said he watched eight of the large drones flying along the Yuma County border near the intersection of U.S. 385 and County Road 54. At the same time, a single drone hovered about 25 miles away over the town of Paoli — it didn’t move all night, just hovered over the town — and eight more drones flew over Haxtun, about 10 miles down the road from Paoli, Myers said.

It sounds like military drones, which probably wouldn't be unexpected in Colorado given the amount of military bases there.