THOUSAND OAKS, Calif. -- Authorities trying to make sense of why aare not publicly discussing what they've learned, but at least one social media post he made after beginning the massacre has emerged as an early focus. Two officials say , a 28-year-old former Marine, apparently paused in the middle of his deadly rampage to post to Instagram.
Social media platforms have scrubbed that and any other posts following Wednesday night's massacre. But one law enforcement official said Long posted about his mental state and whether people would believe he was sane.
Authorities also were investigating whether he believed his former girlfriend would be at the Borderline Bar and Grill, said the official, who was briefed on the investigation but not authorized to discuss it publicly and spoke to The Associated Press on condition of anonymity.
A second law enforcement official, Ventura County Sheriff's Capt. Garo Kuredjian, said that - based on time stamps - the gunman apparently stopped shooting inside the bar and posted to Instagram. Kuredjian said he didn't know the content of any posts.
Instagram and Facebook typically refuse to discuss individual accounts and did not respond to a request for comment. However, a spokesperson from Facebook told CBS News that the gunman did not post a story to Instagram.
Furthermore, in a Facebook update attributed to Long by CNN, which said it was posted around the time of the shootings, he writes: "I hope people call me insane (laughing emojis).. wouldn't that just be a big ball of irony? Yeah... I'm insane, but the only thing you people do after these shootings is 'hopes and prayers'.. or 'keep you in my thoughts'... every time... and wonder why these keep happening..."
Authorities described an attack of military efficiency. None of those injured was hurt by gunfire. When the gunman shot his .45-caliber pistol, he killed. As scores of police officers closed in, Long apparently shot and killed himself.
Several people who knew Long in the suburb of Thousand Oaks where the gunman went to high school and eventually moved back in with his mother described him in disturbing terms.
Long made others feel uncomfortable going back to his teens.
, who coached girls' track and field at the high school where Long was a sprinter, remembers an angry young man who could be verbally and physically combative.
In one instance, Colell said Long used his fingers to mimic shooting her in the back of the head as she talked to another athlete. In another, he grabbed her rear and midsection after she refused to return a cellphone he said was his.
"I literally feared for myself around him," Colell said in an interview Friday. "He was the only athlete that I was scared of."
Colell said she wanted to kick Long off the team, but the boy's coach urged her to reconsider because that could compromise his goal of joining the Marines. She relented when, at the next track meet, Long apologized in front of several coaches and administrators.
Attempts to get comment by phone and in person from officials at Newbury Park High School and its school district were unsuccessful. Both were closed because of a destructive wildfire in the area.
As investigators worked to figure out what set him off, President Donald Trump blamed mental illness, describing the gunman as "a very sick puppy" who had "a lot of problems." At the White House on Friday, Trump touted his efforts to fund work on post-traumatic stress disorder among veterans and ignored questions about stricter gun control laws.
Investigators have not commented on whether mental illness played a role in the rampage. But a mental health specialist who assessed Long after sheriff's deputies responded to a call about his agitated behavior last spring worried he might be suffering from PTSD.
The incident happened in April, when yelling and loud banging noises coming from the home Long shared with his mother prompted a next-door neighbor to call authorities. The mental health specialist concluded there were no grounds to have him involuntarily committed.
Todd Stratton was at the bar Wednesday night. He'd also been friends with Long for 11 years and said he thought he might be suffering from post traumatic stress disorder (PTSD) when he came back from deployment in Afghanistan in 2013.
"There was times where people would ask him about it and he got kind of, you know, upset and said he didn't, you know, like talking about it," Stratton said.
in the shooting rampage were a gunned down as he entered the bar and a U.S. Navy veteran who in which a gunman in a high-rise Las Vegas hotel killed 58 people at an outdoor country music festival.