He wrote, "I'm following reports of an active shooter at the Vets Home in #Yountville".
Yountville is a town of about 3,000 residents in the north San Francisco Bay area. Brenda Espinoza talked to friends inside the home and said they told her a suspect has not yet been caught.
A woman who lives on the property tells KTVU she is safe, and is now on lockdown.
Larry Kamer says his wife, Devereaux Smith, is a fundraiser for the nonprofit Pathway Home.
Authorities are asking people to stay away from the Veterans Home in Yountville.
The sheriff's department asked people to avoid the area.
The gate at the California Avenue home is closed, restricting access to the 300-bed long-term care facility, said Julie Cusator, public information officer.
It is unclear if the shots were live rounds, according to an official from the Veteran's Home. He says officers are working to establish a secure perimeter around the facility and make sure others are safe.
This is the largest veterans home in the United States, housing about 1,100 men and women. The home is near several popular Napa Valley wineries and restaurants and borders Vintners Golf Club, where golfers have been evacuated from the course.
Police closed access to the large veterans home in Yountville after a man with a gun was reported on the grounds. Hostages held in active shooting situation at Yountville veterans homeABC7 News crews at the scene have not heard gunshots but report seeing half a dozen ambulances at the property. The department did not immediately respond to a telephone call from The Associated Press.