President Trump on Friday pointed to Afghanistan military service and post-traumatic stress disorder, or PTSD, as possible reasons a California mass-shooter massacred 12 people in a bar earlier this week.

Some veterans groups said they were concerned about linking the killings to PTSD, a common disorder among troops who have served in war zones, after years of advocacy work trying to remove stigmas and promote treatment.

"He was a war veteran, he was a Marine, he was in the war. He served time, he saw some pretty bad things. And a lot of people say he had the PTSD,” said Trump, who mentioned his own support for mental health funding. “It’s a big problem. People come back, that’s why it’s a horrible thing. They come back, they’re never the same.”

The deceased shooter, Ian David Long, was a Marine who made a seven-month deployment to Afghanistan and he had never sought treatment from the Department of Veterans Affairs, USA Today reported. Long walked into a bar in Thousand Oaks, Calif., on Wednesday night and opened fire on patrons.

Up to 20 percent of veterans who returned from Afghanistan and Iraq suffer from PTSD, which can lead to depression and suicide, and advocates have pushed for wider recognition and more resources for support and treatment.

“The president's remarks were troubling. We reached out this morning to White House staff we regularly work with on veterans issues, making it clear the president's remarks were counterproductive to what we are all trying to accomplish in mental health and veterans health care,” said Joe Chenelly, the national executive director of AMVETS.

Brett Reistad, the national commander of the American Legion, called the shooting “tragic beyond words” but said it should not distract from the work to get treatment for veterans with PTSD.

“The overwhelming majority of combat veterans, with or without PTSD, adjust well and continue to be responsible citizens as they transition back to civilian society,” Reistad said in a statement. “It would be extremely unfair to associate them with such an evil act.”

