Clear Creek County Sheriff Rick Albers describes how officers found the body of Sol Pais near Echo Lake Lodge below Mount Evans, April 17, 2019.

Hart Van Denburg/CPR News

Denver-area public schools, as well as schools in Northern Colorado, were closed Wednesday as the FBI hunted for an armed young Florida woman who was allegedly "infatuated" with Columbine and threatened violence just days ahead of the 20th anniversary of the attack. All classes and extracurricular activities for about a half-million students were canceled as a precaution.

Sol Pais, an 18-year-old Miami Beach high school student, flew to Colorado Monday night and bought a pump-action shotgun and ammunition, authorities said.

"Everything that I've heard in briefings does not indicate she had any friends or assistance in the area, just a fascination with the Columbine area and the horrendous crime that went on there 20 years ago," said Jefferson County Sheriff Jeff Shrader.

The FBI said late Wednesday morning there was "no longer a threat to the community" and later confirmed that she was dead. Sheriff Shrader said she was found near the base of Mount Evans with a self-inflicted gunshot wound.

Had Pais been captured alive, Shrader said she would have "been subject to being taken into custody for a mental health hold."

John McDonald, the head of security for JeffCo schools, said he was "thankful this threat is over and we can get back to the business of learning." Columbine memorial events will continue this weekend with heightened security. District Superintendent Jason Glass said they were working on protocols to handle an event like this in the future.

Gov. Jared Polis said that parents across Colorado, including himself, were "hugging their children a little tighter" today. "Together we thank law enforcement for their swift and diligent actions over the past 24 hours to keep Coloradans safe."

Need To Know More:

What Happened This Morning:

Update 10:37 a.m. — FBI Confirms 'Investigative Activity' Near Mount Evans

The FBI Denver field office tweeted out that authorities are active around the base of Mount Evans outside of Denver. Mount Evans is located about 60 miles west of the city. The road to the summit is currently closed.

Update 10:31 a.m. — What's Going On At Miami Beach High School

Students at Miami Beach High School spent much of the morning behind locked classroom doors after news emerged that authorities were searching in Colorado for a classmate. Eduardo Filipo is a 17-year-old junior at the school and says that teachers locked classroom doors Wednesday as a precaution.

He said he saw Pais frequently at school and that she mostly kept to herself.

Police searched her home in the nearby city of Surfside.

Update 9:57 a.m. — Statement From Gov. Jared Polis

"We know that there is a lot of anxiety right now in Colorado. We want to reassure you that federal, state, and local law enforcement are working together and dedicating all of their resources to locate this dangerous individual. The most important thing that we can do to assist law enforcement is to continue to share the photograph of the suspect and report any information. Coloradans have a history of coming together in times of need and now is no different. Our biggest priority is keeping our children safe. We thank you for your patience while we deal with this threat."

An officer from Jefferson County, Colo., Schools listens on his radio as students leave Columbine High School late Tuesday, April 16, 2019, in Littleton, Colo.

David Zalubowski/AP

Update 9:27 a.m. — What Could Police Do To Hold Her?

Arapahoe District Attorney George Brauchler, speaking to Colorado Matters, said that it is "likely that she would qualify for an M1 hold, an involuntary 72-hour hold," once authorities find and detain her. In terms of Colorado's newly passed "red flag gun bill," Brauchler thought that the new law might have prevented her from obtaining a firearm — but it is not in effect yet.

Update 9:01 a.m. — What Is Known About Sol Pais

A spokeswoman for Miami-Dade County Public Schools said the woman allegedly obsessed with the 1999 Columbine school massacre who authorities are searching for in Colorado is a Miami Beach High School student.

Spokeswoman Jackie Calzadilla said school officials are "fully assisting the FBI in their investigation."

Police were seen removing the large stack of papers Wednesday morning from the single-family home of Sol Pais in Surfside, Florida, a city just north of Miami Beach. Neighbors watched as authorities searched the home.

Denver area schools are closed Wednesday as authorities search for her. The following districts have announced closures:

All schools in the Denver area were urged to tighten security because the threat was deemed "credible and general," said Patricia Billinger, spokeswoman for the Colorado Department of Public Safety. Columbine and more than 20 other schools outside Denver locked their doors for nearly three hours Tuesday afternoon before Wednesday's complete closures were announced.

The Jefferson County Sheriff's Office and the FBI say Pais traveled to Colorado from Miami Monday night and bought a pump-action shotgun and ammunition.

On Tuesday, some schools released their students after additional security was called in and canceled evening activities or moved them inside.

"We always have heightened awareness close to high-profile anniversaries like this," Billinger said.

Authorities said Pais was last seen near Columbine — in the Jefferson County foothills outside Denver — wearing a black T-shirt, camouflage pants and black boots. They appealed for anyone seeing her to call an FBI tip line at 303-630-6227, and said she is too dangerous to be approached by civilians. The alert also said police who come into contact with her should detain her and evaluate her mental health.

"This has become a massive manhunt ... and every law enforcement agency is participating and helping in this effort," Dean Phillips, special agent in charge of the FBI in Denver, said late Tuesday night.

The Denver Post reported that a call to a phone number listed for Pais' parents in Surfside, Florida, was interrupted by a man who identified himself as an FBI agent and said he was interviewing them.

Surfside Police Sgt. Marian Cruz confirmed that her parents last saw her on Sunday and reported her missing on Monday. The Miami Herald and WTVJ report that neighbors say the teen is a senior at Miami Beach High School.