A 16-year-old Colorado high school student, accused of shooting two classmates before taking his own life, had shown an interest in past mass shootings like Columbine and shared neo-Nazi views online, according to reports.The FBI was tipped off about Desmond Holly's online activity in July, Denver TV news stations reported. The Anti-Defamation Leagues (ADL) Center on Extremism said it looked into his online activity."Holly had an account on the gore forum WatchPeopleDie, where he had commented on posts about shootings in Parkland (2018), Buffalo (2022) and at a Quebec City mosque (2017)," the ADL said in a report on Friday.The ADL accuses the teen of collecting tactical gear and adorning it "with extremist symbols," as well as posting "content emulating former shooters such as Rupnow and the 1999 Columbine High School shooters."COLORADO SCHOOL SHOOTER RADICALIZED BY 'EXTREMIST NETWORK,' LAW ENFORCEMENT OFFICIALS REVEALHolly shot himself following Wednesdays shooting at Evergreen High School in Jefferson County. It is still unclear how he selected his victims. The county was also the scene of the 1999 Columbine High School massacre that left 14 people dead.The Jefferson County Sheriff's Office previously said Holly was radicalized by an unspecified "extremist network" but released no details, according to The Associated Press.WHAT LEADS SOMEONE TO COMMIT A MASS SHOOTING? TRUMP ADMIN, RFK JR PLAN TO FIND OUT"Hollys TikTok accounts were filled with white supremacist symbolism," the ADL said. The name of his most recent account included a reference to a popular White supremacist slogan. The account was unavailable Friday. TikTok told the AP the accounts associated with Holly had been banned.On Sunday, Sen. Chris Coons, D-Del., told CBS' "Face the Nation" that the internet was "driving extremism in our country" following the assassination of Charlie Kirk."Young people can readily access extremist content and visual depictions of graphic violence that are celebrated by users of the platform, potentially desensitizing them to such content and increasing the risk of ideologically-motivated violence," the ADL said.St. Anthony Hospital in Lakewood, Colorado, did not immediately respond to a Fox News Digital inquiry about the condition of the two victims who were last said to be undergoing treatment there. It is not yet clear if Holly targeted the victims or if they were shot at random, Jefferson County Sheriffs Office spokesperson Jacki Kelley said during a news conference.FBI Director Kash Patel said on Thursday that the Denver field office was continuing to coordinate with partner agencies to investigate the shooting. The agency did not immediately respond to a Fox News Digital inquiry.Fox News Digital's Sophia Compton and The Associated Press contributed to this report.