Investigators know who the gunman is and they know he is armed with a rifle.
Robertson says the gunman released some hostages and kept the three.
The home has been in contact the California Highway Patrol, which provides public safety help because the home is a state facility, Cusator said.
"We have activated our emergency response protocol and are cooperating with law enforcement". He didn't give a motive for the gunman's actions.
The Veterans Home of California opened in 1884 and is the oldest veterans home in the country.
Jan Thornton was among hundreds of relatives anxious sick about their loved ones. It is located in Yountville, north of San Francisco.
Thornton says she's still shaking and that she hasn't been able to talk to her father. Thornton said she was anxious about how her dad's coping with the stress, considering his age, PTSD and slight dementia.
Former Trump campaign chairman Paul Manafort pleads not guilty to charges
Paul Manafort last week pleaded not guilty in a related case in Washington, D.C., where he is set to go to trial September 17. Prosecutors had offered to combine the indictments in the District, but Manafort refused to do so.
Serena Williams return to Professional tennis this Thursday
Williams won the match in straight sets, 7-5, 6-3, and will now go on to face No. 29 Kiki Bertens in the next round. She was originally scheduled to return at the 2018 Australian Open , but withdrew because she felt she wasn't ready.
Rams Trade LB Alec Ogletree to Giants for Two Draft Picks
This had helped him earn a lucrative four-year, $42.7 million extension in October 2017 that had $30 million guaranteed. He had 95 tackles and two sacks last season while moving into coordinator Wade Phillips' 3-4 defensive scheme.
She was able to speak with him by phone, according to AP.
He does not know if the shooter was a veteran receiving treatment from the home.
An armoured police vehicle, ambulances and several fire trucks were at the scene.
The Napa County Sheriff's Office said officers responded to the Veterans Home of California in Yountville around 10:45 a.m. local time and a shelter-in-place order was issued.
It is unclear if the shots were live rounds, according to an official from the Veteran's Home.
Mr Fransen said authorities were working to establish a secure perimeter around the facility, which is home to about 1,000 residents.
The home, which houses around 1,000 Iraq and Afghanistan veterans, has been put into lockdown as authorities surround the property.