LITTLETON, Colo. (AP) — Authorities said Tuesday that they are looking for a young woman who is "infatuated" with the 1999 shooting at Columbine High School and made threats just days before the 20th anniversary of the attack that killed 13 people.

The undisclosed threats led Columbine and several other high schools outside Denver to lock their doors for nearly three hours. All students were safe, school officials said.

Sol Pais, 18, traveled to Colorado on Monday night and has tried to buy firearms, according to the Jefferson County Sheriff's Office and the FBI. Pais was last seen in the foot...