The cause of last week’s sudden shutdown of the National Solar Observatory (NSO) in Sunspot, New Mexico, by FBI agents with no explanation given to the public, remains shrouded in mystery, giving rise to all kinds of guesswork and conspiracy theories.

Some people theorized that the state-of-the-art technology inside the facility in the Sacramento Mountains had spotted something that should be kept away from public eyes, such as extraterrestrial life, UFOs or signs of the sun gradually switching off, The Independent wrote.

Although the FBI and the facility’s administration have pointed to some “security issue” as the cause of the lockdown, the mere fact that the observatory is only about 120 miles from the site of the Roswell UFO incident has only fueled speculation.

In a statement posted on the observatory’s Facebook page on Sunday, the observatory apologized for “the continued closure of the facilities.”

“The Association of Universities for Research in Astronomy (AURA) is addressing a security issue at the National Solar Observatory facility at Sacramento Peak, New Mexico and has decided to temporarily vacate the facility as a precautionary measure,” the statement said.

“AURA, which manages Sacramento Peak with funding from the National Science Foundation, is working with the proper authorities on this issue. We have no further comment at this time,” it added.

The statement set off a flurry of comments, with followers wondering why the NSO refused to come clean about what had happened.

“Why don’t you just tell us what is going on?” wrote one. “This is not cool. FBI needs to be frank.”

Observatory officials have not confirmed media reports that the FBI was involved in the shutdown.

“It was our decision to evacuate the facility,” AURA spokeswoman Shari Lifson said, according to the Alamagordo Daily News. “I am actually not sure (when the facility was vacated) but it will stay vacated until further notice,” he added.

The Sunspot National Observatory, which is run by the Association of Universities for Research in Astronomy (AURA), was evacuated on September 6.

AURA says they ordered the evacuation but, oddly, that they also aren't sure when exactly it was vacated.

READ MORE: FBI Closing Down Solar Observatory, Spawns Alien Conspiracy Theories — Reports

When it was shut down, the FBI came in but "refused" to tell local authorities "what's going on," Otero County Sheriff Benny House said, adding that the bureau told his department to stand by while they evacuated the building.