Will Simmons felt a sickening sense of familiarity when news bulletins scrolling across his computer screen Monday identified the Washington Navy Yard shooter as a veteran.
"I thought, 'Here we go again,' " recalled Mr. Simmons, 31, an Iraq war veteran who was at his pharmaceutical office job in New Jersey that day. "It's going to turn into a disgruntled veteran story. It was like a punch in the gut to see it was a vet."
Many veterans groups and advocates complain that news media portrayals of onetime Navy reservist Aaron Alexis as a troubled veteran plays into a stereotype that causes problems for former members of the military.
"They talk about it like it's some sort of explanation," said Tom Tarantino, chief of policy for Iraq and Afghanistan Veterans of America. "It perpetuates the stigma of the ticking time bomb or disturbed vets. To talk about it as relevant is not only insulting, but it also does a disservice to hundreds of thousands of veterans."
Some warn that calls to clamp down on security clearances for federal workers and contractors who have mental-health issues could discourage veterans from seeking treatment for post-traumatic stress disorder. On Wednesday, Defense Secretary Chuck Hagel ordered a broad review of the security clearance procedures.
Mr. Simmons said he was concerned about assumptions that the attack was tied to Alexis' military service and speculation about possible post-traumatic stress. Alexis did not deploy for overseas service.
"As someone diagnosed with PTSD, that was pretty offensive," said Mr. Simmons, who served at Balad Air Base in 2007 with an Air Force Office of Special Investigation unit that came under fire during counterterrorism operations. "Shooter-veteran-PTSD -- it all gets lumped together."
Meg Mitcham, who served as an Army medic in Iraq in 2005 and 2006 and has been diagnosed with post-traumatic stress, said she is concerned the talk of stripping the security clearances of people with mental-health disorders will derail military efforts to end the stigma surrounding PTSD.
"I worry if we start going down that road, service members won't seek help for mental health," said Ms. Mitcham, who noted that losing her security clearance would hurt future job prospects. "There's been a lot of effort put into convincing service members that they won't lose their security clearance and that it won't affect their careers."
Veterans make up about a quarter of the federal workforce, and many have been treated for mental-health issues. In 2012, Veterans Affairs provided mental-health treatment to 1.2 million veterans, including 502,546 veterans who were treated for PTSD.
Under current procedures, service members who have sought help for post-traumatic stress are not flagged for additional review in background checks.
Phillip Carter, a former Army officer who served in Iraq and is now a fellow with the Center for a New American Security, also worries some may avoid needed treatment to protect a security clearance.
Mr. Carter used Twitter to criticize as "irresponsible" a headline Monday evening on The Washington Post website that read, "Navy Yard gunman said to be troubled veteran."
"The headlines and general narrative are getting ahead of the facts," Mr. Carter said. "I put this in the category of workplace violence. There is still no evidence that anything in his service record caused him to kill these people."
A CNAS report on veteran employment last year said companies consistently cite concerns about PTSD as a negative stereotype that could hurt the chances of a veteran being hired.
"It hurts them in the workplace," Mr. Carter said. "It hurts them in a university setting. It hurts them in family situations."
Noted Mr. Simmons, "I had a former boss say, 'You're not going to shoot everybody up, are you?' " He was stunned by the question, he recalls, and had to walk away. Now he is concerned others think the same.
"You're wondering if they're thinking about the Navy Yard," Mr. Simmons said. "With incidents like this, you've got to wonder if they're wondering."