The FBI's Rocky Mountain Safe Streets Task Force issued a notice Tuesday describing Pais as "infatuated with (the) Columbine school shooting". The sheet also says, "If contacted detain and evaluate mental health status then contact Det".
"Last night, Sol Pais traveled to Colorado & made threats".
"She can, please, come home". Some say they just want to pay their respects, but others claim they are in love with the shooters - or sometimes that they have been reincarnated with the shooters' souls.
Sol Pais, 18, flew to Denver from Miami and bought a pump-action shotgun and ammunition, said Dean Phillips, special agent in charge of the Federal Bureau of Investigation in Denver. "She is armed and considered to be extremely unsafe", the office wrote on Facebook.
All schools in the Denver metropolitan area were placed on lockdown on Tuesday in response to the threats.
Patricia Billinger, a spokeswoman for the Colorado Department of Public Safety, says the agency made the recommendation because Tuesday's threat was deemed "credible and general".
Aurora Public Schools, east of Denver, said all of its schools were "placed in secure perimeter".
Jefferson County Sheriff's Office said in a Tuesday Facebook post that officials were looking for an 18-year-old woman who allegedly made threats.
She is described as an 18-year-old white female from Florida last seen in the area wearing camouflage pants, a black t-shirt and black boots.
"If we found her tonight, we will certainly hold her for as long as we can legally", Phillips said.
Authorities said Pais was last seen in the foothills west of Denver, was considered armed and extremely unsafe and should not be approached. They were not directed to a particular school, according to sheriff's spokesperson Mike Taplin.
People visit the Columbine memorial after teens kicked off a voter registration rally, a day ahead of the 19th anniversary of the massacre at Columbine High School, in Littleton, Colorado, U.S., April 19, 2018.
Students leave Columbine High School.
Police say they received a "credible threat", but, the threat did not name a specific school.
Two hours after announcing the lockouts, the school system reported that all students and staff were safe, adding that students would be released from the schools and buses would run on their normal schedule, though some may be slightly delayed. They notified area schools that afternoon.
The lockdowns come just days before the 20th anniversary of a mass shooting at the school that killed 12 students and a teacher.
The 20th anniversary of the shooting at Columbine High School is days away.
Officials didn't provide further details or reveal where Pais traveled from, saying it would compromise their investigation. There was no immediate indication whether there was any connection to the anniversary. Extra precautions were taken at schools near Columbine, where sheriff's deputies were on hand.