The man who opened fire in a Lake Hefner, Oklahoma restaurant and shot three peoplethis past week was investigated twice by federal agents after concerns were reported regarding his YouTube channel, FBI officials announced Sunday.FBI spokesperson Andrea Anderson said the agency received a call to its public access line earlier in May and received an informal call earlier in 2018 about 28-year-old Alexander Tilghman's YouTube channel. "In response to Thursday's shooting in Oklahoma City, a review of FBI databases were conducted and it was determined that one call was made to our Public Access Line (PAL) earlier this month regarding the shooter identified as Alexander Tilghman," Anderson said in a news release. "The caller reported concerns about a YouTube channel associated with the subject, but did not report any potential threat of violence and did not have any knowledge of the subject possessing any weapons. Based on this information, and following our standard protocol, no further investigation was warranted."In addition, earlier this year, FBI Oklahoma City Division had received an informal tip regarding the same YouTube channel. The content found on this channel at that time was identified as First Amendment-protected speech, and no further action was taken."Around 6:30 p.m. Thursday, officers responded to reports of a shooting at Louie's on the Lake. Three people -- a woman and two children -- were injured in the shooting before two armed citizens shot and killed Tilghman.Authorities said Tilghman's social media posts were filled with evidence of mental illness that was consuming him. He even said in the videos that drones were spying on him and that he could see demons."I want to show you how Satan has taken over my computer. That includes my cellphone," Tilghman said in one YouTube video.Tilghman posted more than two dozen videos to YouTube.His brother said Tilghman had serious mental issues and the shooting was a sign that he was crying for help.Tilghman's former roommate, Dylan Michael Karns, said Tilghman had been making those videos and claims since 2012. Karns also said he remembers his old roommate talking about demons."There was one day I was watching TV and he just went up and turned it off. I said, 'What's wrong?' He said, 'The demons, man. They're in there,'" Karns said. "Just based off of 10 minutes of knowing him, I wouldn't have given him a gun."Briana Jones, a spokesperson for Oklahoma Children's Hospital, told The Associated Press on Sunday that one of Tilghman's victims -- a 12-year-old girl who underwent surgery after being shot in the stomach -- is recovering. Although she's still hospitalized, officials said the girl is in good condition.The girl's mother and a 14-year-old friend were also shot. The mother was treated after being grazed by bullets.The hospital spokesperson told the AP she didn't have information about the 14-year-old girl. Police have said she was shot in the arm or wrist.Oklahoma City police are still looking for a motive behind the shootings and, for now, they're calling the incident "random."