A young Florida woman who the FBI said was “infatuated” by the mass shooting 20 years ago at Columbine High School has been found dead.

The FBI conducted a massive manhunt for Sol Pais, 18, after she flew to Colorado this week and bought a pump-action shotgun. She had made threats ahead of Saturday’s 20th anniversary of the mass shooting that killed 13 people at Columbine. The FBI described her “extremely dangerous” and after a lengthy search, she was discovered by agents with an apparent self-inflicted gunshot wound.

The FBI said she “made threats to commit an act of violence in the Denver metropolitan area.” In response, “All schools in the Denver area were urged to tighten security because the threat was deemed ‘credible and general,’ said Patricia Billinger, a spokeswoman for the Colorado Department of Public Safety,” the Associated Press reported. “Columbine and more than 20 other schools outside Denver lock their doors for nearly three hours Tuesday afternoon before Wednesday’s complete closures were announced.”

In 1999, Twelfth graders Eric Harris and Dylan Klebold murdered 12 students and a teacher at Columbine before committing suicide.

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The @FBIDenver & JCSO are asking for the public’s help regarding a potential credible threat. Last night Sol Pais traveled to Colorado & made threats. She is armed & considered to be extremely dangerous 1/3 pic.twitter.com/2x5iwddsMp — Jeffco Sheriff (@jeffcosheriffco) April 16, 2019

Before she was found dead, Dean Phillips, head of the Denver office of the FBI, which is leading the investigation, said there was a “massive manhunt” for Pais, according to the Washington Post. Pais was “last seen in the county’s foothills, clad in camouflage pants, black boots and a black T-shirt,” the Post reported.

FBI agents were seen entering Pais’s home in South Florida Tuesday night. A man who identified himself as her father told the Miami Herald of his daughter: “I think maybe she’s got a mental problem.” Pais’s parents reported the teenager missing Monday night, after losing contact with her on Sunday. “Because of her comments and her actions, because of her travel here to the state, because of her procurement of a weapon immediately upon arriving here,” he said, “we consider her to be a credible threat — certainly to the community and, potentially, to schools.” The threat, which the FBI said was “not isolated to one school or individual,” led county public school officials on Tuesday afternoon to place Columbine and nearby schools on “lockout,” which means classes continue as usual inside while entries to and exits from the building are restricted.