A police spokesman said that the bodies of the victims were found dead alongside that of the gunman at 02:00GMT.
Department of Defense officials said Wong was a decorated USA soldier who served on active duty from May 2010 to August 2013.
Jennifer Golick's father-in-law, Bob Golick, told the AP that Golick had recently kicked Wong out of the program. Wong was described as an expert marksman.
Hostage negotiators from at least three different agencies, including the Federal Bureau of Investigation, were on site to make contact with the gunman on his cell phone, Childs said.
According to her Linked In page, Golick was clinical director at the Pathway Home.
The Napa Valley Performing Arts Center at Lincoln Theater, a 1,200 seat venue located on the grounds of the Veterans Home of California, is a comprehensive performing arts center dedicated to the cultural and artistic wellbeing of the Napa Valley.
#Trade: EU to seek clarification on USA proposals before imposing counter measures
She did not say what level of tariffs the European Union would set, leaving it unclear what the economic impact would be. President Donald Trump's proposed trade tariffs are "a bad call".
Authorities did not identify the workers or the gunman because they said they were still notifying relatives.
President Donald Trump has tweeted he is "deeply saddened" by the shooting that took the lives of three women who worked at a California veterans centre.
California Gov. Jerry Brown and wife Anne have offered their condolences to families and friends of the three women killed by a gunman in a Northern California veterans home.
The Democratic governor ordered state Capitol flags flown at half-staff.
Wong slipped into a going-away party for some employees of The Pathway Home, a non-profit post-traumatic stress disorder program. The Pathway Home said Gonzales was a clinical psychologist in San Francisco with the Department of Veterans Affairs.
Authorities tried for hours to contact him after he took the hostages, without success, said Sheriff John Robertson.
'Let them call you racists,' Bannon tells far-right French party
The younger Le Pen has said the proposed name change is needed to show that the party had become "adult", The Guardian reported. To that end, rebranding the National Front's image is the primary goal of the "party congress" in Lille this weekend.
The Veterans Home of California in Yountville, the largest such facility in the United States, was the scene on Friday of the latest mass shooting to rock a country already shocked by the slaughter last month of 17 people at a Florida high school.
It was "far too early to say if they were chosen at random" because investigators had not yet determined a motive, California Highway Patrol Assistant Chief Chris Childs said.
The Veterans Home posted on their Facebook page that emergency response protocols were activated and they were working with law enforcement. Childs added that a bomb-sniffing dog had alerted on the suspect's auto but no bombs were found in the vehicle.
James Musson, a 75-year-old Army veteran and resident of the facility, told Reuters many who lived there voiced concerns about lax security, saying visitors could walk in and out without restriction and that public safety officers were not armed.
A USA official had earlier confirmed the deaths to The Associated Press.
Victims, gunman identified in Yountville veterans home shooting tragedy The governor has issued this statement: "Anne and I are deeply saddened by the terrible violence at the Yountville Veterans Home, which tragically took the lives of three people dedicated to serving our veterans".
13 milliards d'euros de contrats annoncés — Macron en Inde
Il entend notamment tirer du retrait de la Grande-Bretagne, partenaire historique de l'Inde, de l'Union européenne avec le Brexit. La région de l'océan Indien va jouer un rôle très significatif", a estimé Narendra Modi lors d'une allocution conjointe.
The official wasn't authorized to discuss the matter publicly and spoke to The Associated Press Friday on condition of anonymity.