LOS ANGELES, April 17 (Xinhua) -- Schools in the Denver area in the western U.S. state of Colorado are closed Wednesday as authorities are searching for a woman whom they described as "armed and dangerous."

Police and FBI are searching for Sol Pais, who traveled to Colorado and made threats on Monday night, said local police, adding that the woman is "armed and considered to be extremely dangerous."

"She is a white female, 18 years old, approximately 5'5" in height, with brown hair. She was last seen wearing a black t-shirt, camouflage pants, and black boots. She was last seen in the foothills of Jefferson County," twitted Jefferson County Sheriff and released photos of the woman to ask for public help.

The woman went to a store and bought a pump action shotgun and ammunition after she arrived in Colorado, said authorities.

"In collaboration with other Denver-metro area school districts, all Denver Public Schools will be closed on Wednesday, April 17 due to the ongoing safety concern," Denver Public School District announced Wednesday morning.

"All facilities and programs are closed for the day," tweeted the school district.