Columbine massacre 'infatuated' teenager found dead while on run from FBI

A teenager who had a suspicious obsession with the 1999 Columbine massacre has been found dead after flying to the city in which the deadly shooting spree took place.

It had been reported 18-year-old Sol Pais bought a pump-action shotgun and ammunition upon arrival in Denver before disappearing and leaving bewildered FBI investigators scouring the area.

The FBI in Denver confirmed news of her death in a tweet, writing: "We can confirm that Sol Pais is deceased.

"We are grateful to everyone who submitted tips and to all our law enforcement partners for their efforts in keeping our community safe."

The 18-year-old had reportedly threatened several schools including Columbine - the place 17-year-old Dylan Klebold and 18-year-old Eric Harris massacred 12 students and a teacher 20 years ago.

Dylan Klebold (left) and Eric Harris (right) killed 12 of their fellow pupils. Credit: AP

The undisclosed threats led over 20 schools to go into lockdown for nearly three hours because of the potential threat.

Pais was last seen in the foothills west of Denver - just days before the 20th anniversary of the Columbine shooting this week, authorities said.

She was being considered armed and extremely dangerous, with police warning she should not be approached.

The FBI’s Rocky Mountain Safe Streets Task Force issued a notice on Tuesday describing Paris as “infatuated with (the) Columbine school shooting”.

The alert also said police who come into contact with her should detain her and evaluate her mental health.

Dean Phillips, of the FBI in Denver said the threats she made were general, not specific to any school.

"She has made some concerning comments in the past… and because of that we were concerned," he said.

Before the discovery she was dead Jefferson County sheriff Jeff Shrader told MSNBC on Wednesday that every April brings about Columbine copycat threats but said Pais' interest in the school stood out.

"We do get a number of threats each April that come up and, obviously, with Columbine having its 20-year anniversary, it perhaps heightened some of those sensitivities," he said.