Three women who devoted their lives to helping traumatised veterans were killed by a patient who had been kicked out of their Northern California treatment program, authorities and a relative of a victim say.
A day-long siege at The Pathway Home ended on Friday evening with the discovery of four bodies, including that of the gunman.
He was identified as Albert Wong, 36, a former Army rifleman who served a year in Afghanistan in 2011-2012.
The victims were The Pathway Home executive director Christine Loeber, 48; clinical director Jennifer Golick, 42; and Jennifer Gonzales, 29, a clinical psychologist with the San Francisco Department of Veterans Affairs Healthcare System.
"These brave women were accomplished professionals who dedicated their careers to serving our nation's veterans, working closely with those in the greatest need of attention after deployments in Iraq and Afghanistan," The Pathway Home said in a statement.
Investigators were still trying to determine when and why Wong killed the three. The Pathway Home, a non-profit post-traumatic stress disorder program at the Veterans Home of California-Yountville in the Napa Valley wine country region.
Governor Jerry Brown ordered flags flown at half-mast at the capitol in memory of the victims.
President Donald Trump tweeted on Saturday morning: "We are deeply saddened by the tragic situation in Yountville and mourn the
Golick's father-in-law, Bob Golick, said in an interview she had recently expelled Wong from the program.
The Pathway Home is located on the sprawling campus of the veterans centre, which cares for about 1000 elderly and disabled vets.
It is the largest veterans home in the nation, according to the state Department of Veterans Affairs.
Wong went to the campus about 85 kilometres north of San Francisco on Friday morning, slipping into a going-away party for some employees of The Pathway Home.
Larry Kamer told The Associated Press that his wife, Devereaux Smith, called him to say that the gunman had entered the room quietly, letting some people leave while taking others hostage.
Golick called her husband, Mark, to say that she had been taken hostage by the former soldier, her father-in-law said.
Mark Golick didn't hear from her again.
A Napa Valley sheriff's deputy exchanged gunshots with the hostage-taker at about 10.30am but after that nothing was heard from Wong or his hostages despite day-long efforts to contact him, authorities said.
The bodies of Wong and the women were found at about 6pm. While authorities had the building under siege for about eight hours, they didn't enter it.