LITTLETON, Colo. — A Florida student who authorities say was obsessed with the Columbine school shooting and may have been planning an attack of her own in Colorado just days ahead of the 20th anniversary was found dead Wednesday in an apparent suicide after a nearly 24-hour manhunt.

Jefferson County Sheriff Jeff Shrader said Sol Pais, 18, was discovered by the FBI with what appeared to be a self-inflicted gunshot wound.

The manhunt had led to the closing of Denver-area schools as a precaution, with classes and extracurricular activities canceled for a half-million students.

During the urgent search, the FBI said Pais was “infatuated” with the 1999 mass shooting at Columbine High School and made threats against the Denver area ahead of Saturday’s anniversary of the attack that killed 13 people.

The Miami Beach high school student flew to Colorado on Monday night and bought a pump-action shotgun and ammunition from a gun shop in Littleton, not far from Columbine, authorities said.

The FBI described Pais as “extremely dangerous.”

“We’re used to threats, frankly, at Columbine,” John McDonald, executive director of security for the Jefferson County school system, said when the manhunt was over. “This one felt different. It was different. It certainly had our attention.”

Her body was found off a trail not far from the base of Mount Evans, a popular recreation area about 60 miles southwest of Denver, authorities said.

McDonald described her trip as a “pilgrimage” to Columbine and cited her purchase of the shotgun as one reason officials took her as a serious threat.

Colorado Gov. Jared Polis said after receiving word that the hunt was over that he and all Colorado parents are “hugging their children a little tighter.”

Authorities said Pais was last seen in the Jefferson County foothills outside Denver wearing a black T-shirt, camouflage pants and black boots.

Police were instructed to detain her for a mental health evaluation.

The sheriff said the sale of the shotgun apparently followed the state’s legal process. Out-of-state residents who are at least 18 can legally buy shotguns in Colorado. Gun buyers must provide fingerprints and pass a criminal background check.

In Pais’ Florida hometown, Surfside Police Chief Julio Yero asked that the family be given “privacy and a little time to grieve.”

“This family contributed greatly to this investigation from the very onset. They provided valuable information that led us to Colorado and a lot of things that assisted in preventing maybe more loss of life,” he said.

Pais’ parents last saw her Sunday and reported her missing Monday night, Surfside police said.

Authorities said she did not single out a specific school.

Jefferson County school officials said events planned to mark the anniversary this weekend will go on as scheduled, including a ceremony Saturday at Columbine.

Two teenage gunmen attacked Columbine on April 20, 1999, killing 12 classmates and a teacher before taking their own lives. The massacre has inspired cult-like admirers and motivated other mass shooters over the decades.

Adam Charni, a Miami Beach High School senior, said Pais dressed in black and kept mostly to herself. He said he was “baffled” to learn she was the person authorities in Colorado were searching for. Another classmate, Drew Burnstine, 17, described Pais as quiet and smart.