The first call came in around 7:30 a.m. The caller described the weapon in question as a shotgun.
An "extensive search via ground and air" was underway for hours to locate the reported woman or weapon, California Highway Patrol said, but nothing was found. A weapon was not recovered either. CHP was the lead agency on site.
Just before noon, the Napa County Sheriff issued a statement saying police activity "has concluded and is clear."
The facility was on lockdown for the duration of the search. A shelter-in-place was also ordered for the Napa County town and people were asked to stay away from the area.
There were no shots fired and Queen of the Valley Medical Center in Napa did not receive any patients regarding the incident.
VIDEO: Yountville Veterans Home lockdown scary reminder of shooting 3 years ago
Yountville Veterans Home lockdown scary reminder of shooting 3 years ago
CHP said several of its units would remain on scene Tuesday afternoon "out of an abundance of caution," but the home was resuming normal operations.
Tuesday's scare was a reminder of the shooting at the home in March 2018, when a gunman killed three health care staff. Christine Loeber, Jennifer Gray Golick, and Jennifer Gonzales Shushereba were all killed in the attack.
Since then, local law enforcement officer described residents as being "justifiably jumpy." No sighting has prompted this large a response, or lasted so long.
Police on high alert after report of Yountville armed woman
The 2018 attack happened in the Pathway Home, a residential therapy program on site. The Pathway Home has not reopened since.
In some ways, the pandemic has further tightened security with temperature checks and a closer look at IDs.
"Since the last time when people were killed, our personnel here don't carry guns, so CHP has like seven full-time operatives," said Donald Ford, a longtime resident. He said he was impressed by how quickly officers knocked on doors and warned people to stay inside Tuesday morning.
Officers were on site within three minutes of the first call.
The Veterans Home of California-Yountville is the largest home for veterans in the United States.