Three years after a former patient at the Veterans Home of California in Yountville shot and killed three women, the complex was on lockdown and swarmed with law enforcement and media Tuesday morning following reports of an armed woman on the campus.

As ABC 7 reports, a woman armed with a long gun of some kind was first reported at 7:30 a.m. Tuesday, and Napa County deputies responded in force. Still there was no report of shots fired. Authorities issued a shelter-in-place order for all of Yountville Tuesday morning.

The Napa County Sheriff’s Department SWAT team arrived at the site by 8:30 a.m., according to the Press Democrat, and California Highway Patrol officers are on the scene as well. The suspect was still being referred to as a "possible active shooter."

But, as the Napa Valley Register reports, after several hours of searching and investigating, law enforcement officers still could not confirm any shots fired, and still could not locate a suspect. The woman had been reported in the vicinity of the Holderman building, the paper reports, and SWAT members searched the building "from top to bottom," but never located a suspect.

Now authorities are investigating what triggered the alarm and who gave the report of the armed the woman.

The veterans' complex was the site of a March 2018 shooting in which a former patient and Army veteran who had sought treatment there for PTSD, Albert Wong, walked in and shot three female employees before taking his own life. Confusion about what transpired after Wong had taken three hostages and let everyone else go led to a five-and-a-half-hour standoff delay, because the only deputy who had come close to the scene was not clear that Wong had taken his own life and three others.

That incident was also handled by the CHP along with Napa County Sheriff's deputies.

The state-owned veterans home has around 730 residents and is the largest veterans home in the U.S., with around 850 employees.

Photo: CalVet/YouTube

*This post has been updated throughout.