YOUNTVILLE, Calif. (Reuters) - Details emerged on Saturday about a decorated former U.S. serviceman who took three women hostage at a California veterans home where he had undergone treatment for PTSD, in a standoff that ended when police found him and his captives dead.

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 still shocked by the slaughter last month of 17 people at a Florida high school.

Officials named the gunman as Albert Wong, 36, of Sacramento, and said he had served with the U.S. Army on active duty from May 2010 to August 2013 and spent a year in Afghanistan. He received four medals including an Afghanistan campaign medal and was awarded an Expert Marksmanship Badge with Rifle, the Pentagon said.

Wong had been a patient of Pathway Home, a program at the Yountville complex for former service members suffering post-traumatic stress disorder after deployments in Iraq and Afghanistan. The San Francisco Chronicle, citing unnamed sources, said he had been asked to leave the program two weeks ago.

Yountville Mayor John Dunbar, who also serves as a board member of the Pathway Home, said the facility and the town mourned the loss of the three women.

“We also lost one of our heroes, who clearly had demons that resulted in the terrible tragedy that we all experienced here,” he told reporters.

The incident began at about 10:30 a.m. PST on Friday at the sprawling facility about 60 miles north of San Francisco and ended almost eight hours later.

According to Larry Kamer, the husband of one of the Pathway Home administrators, Devereaux Smith, Wong walked into the program’s building carrying a rifle during a going-away party for one of the employees.

Kamer, who volunteers at the home, said his wife told him by phone during the siege that the gunman had let her and three other women leave the room where the party was taking place, but that he kept three female employees behind as hostages.

The hostages who died were named as Pathway Home Executive Director Christine Loeber, 48; the program’s clinical director, therapist Jen Golick, 42; and Jennifer Gonzales, 29, a psychologist with the San Francisco Department of Veterans Affairs Healthcare System.

“Each of them brought energy, vitality, personality to their jobs, and that’s so critical when we’re talking about supporting our veterans who have post-traumatic stress or traumatic brain injury in particular,” Dunbar said.

Despite repeated efforts by police negotiators, authorities said they had failed to make contact with the gunman after he exchanged fire with a sheriff’s deputy at the start of the standoff.

Officers who eventually entered the room where the hostages were being held found all four bodies there, police said. No details were immediately given about how they died.

President Donald Trump said on Twitter, “We are deeply saddened by the tragic situation in Yountville and mourn the loss of three incredible women who cared for our Veterans.”

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.

Dunbar said the deaths were the first “serious incident” at the home since it began to treat veterans more than 10 years ago. He was scheduled to meet officials from the California Department of Veterans Affairs to discuss how to move ahead.

The siege came less than a month after a former student killed 17 people at a high school in Parkland, Florida, using an assault-style rifle. That massacre sparked a student-led drive for new restrictions on gun sales to curb mass shootings.