The gunman and a CHP deputy exchanged fire, he said, but there were no immediate reports of injuries, he said.
Bay Area quoted a local fire captain as saying that a gunman had taken hostages inside the home.
As many as 30 shots rang out near the facility's main dining hall, according to KQED..
The Veterans Home of California opened in 1884 and is the oldest veterans home in the country.
Jan Thornton of Vallejo, California, was among hundreds of relatives anxious how their loved ones were coping with the lockdown.
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. He told KTVU a gunman quietly came into a going-away party and staff meeting and let some leave, while keeping others hostage.
Though she thinks her dad is safe, she is still anxious about the stress of the situation, considering his age and that he has post-traumatic stress disorder and some dementia. Amanda Vargas, whose husband is the chief of finance in the home's administrative building, said she's been in touch with her husband and he is safe.
The hostages are employees of the facility's Pathway Home, a privately run program treating veterans of the Iraq and Afghanistan wars who suffer from post-traumatic stress disorder, cops said. "This is a little community and we all know each other".
According to California Department of Veterans Affairs, the Veterans Home of California in Yountville dates back to 1884 and is considered the largest veterans home in the US with more than 1000 veterans from all wars dating back to World War II.
He does not know if the shooter was a veteran receiving treatment from the home.