The Federal Bureau of Investigation and Colorado authorities are asking for the public's help in locating a woman who allegedly made threats prompting lockouts at a number of schools Tuesday.

Sol Pais, 18, traveled to Colorado on Monday night and made threats in the Denver metropolitan area, according to the sheriff's office in Jefferson County, Colorado.

Pais is armed and considered to be extremely dangerous, according to the sheriff's office.

Tuesday afternoon, Jeffco Public Schools had placed 21 schools, two outdoor labs and a transportation terminal on lockout due to police activity. Included in that lockout was Columbine High School, where two students killed 12 other students and a teacher in a mass shooting on April 20, 1999.

CNN reports that a sheriff's office spokeswoman called the threats from Pais "credible," but said they were not directed toward a specific school.

Jeffco Public Schools spokesperson Diana Wilson said "everyone is safe," Denver7 reported. 

Pais is described as a white female standing roughly 5'5" tall with brown hair. She was last seen wearing a black t-shirt, camouflage pants and black boots in the foothills of Jefferson County.

Anyone with information on her whereabouts is encouraged to call the FBI tip line at 303-630-6227. Anyone who sees Pais should not approach her, as she is considered armed and dangerous.