LITTLETON, Colo. (AP) - A young Florida woman who traveled to Colorado and bought a shotgun for what authorities feared would be a Columbine-inspired attack 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 18-year-old Sol Pais was discovered by the FBI with an apparent self-inflicted gunshot wound.

The manhunt had led to the closing of Denver-area schools as a precaution.

During the manhunt, the FBI said Pais was "infatuated" with Columbine and made threats ahead of Saturday's anniversary of the attack that killed 13 people at Columbine High School in 1999. The FBI described her "extremely dangerous."

The Miami Beach high school student flew to Colorado on Monday night and bought a pump-action shotgun and ammunition, authorities said.

"We deal with a lot of threats 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 got our attention."

Agents had focused the search around the base of Mount Evans, a popular recreational area about 60 miles southwest of Denver.

All classes and extracurricular activities for about a half-million students were canceled as a precaution, though sheriff's spokesman Mike Taplin said the young woman's threats were general and not specific to any school.

Authorities said Pais was last seen not far from Columbine - in the Jefferson County foothills outside Denver - in a black T-shirt, camouflage pants and black boots. Police were instructed to detain her for a mental health evaluation.

In Pais' hometown of Surfside, Florida, 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 on Sunday and reported her missing to Florida authorities on Monday night, Surfside police said.

Because of the threats, Columbine and more than 20 other schools outside Denver locked their doors for nearly three hours Tuesday afternoon, and some canceled evening activities or moved them inside.

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.

Two teenage gunmen attacked Columbine on April 20, 1999, killing 12 classmates and a teacher before taking their own lives.