Columbine High School principal Scott Christy, right, joins an officer as students leave the school, April 16, 2019, in Littleton, Colo. Authorities say they are looking for a woman suspected of making threats.
FILE - Columbine High School principal Scott Christy, right, joins an officer as students leave the school, April 16, 2019, in Littleton, Colo. Authorities say they are looking for a woman suspected of making threats.

Police in the U.S. state of Colorado are searching for an 18-year-old woman suspected of making threats that led to a lockout at several Denver-area schools. The threat comes just days before the 20th anniversary of a mass shooting at Columbine High School in Littleton, Colorado.

The FBI and local police identified the woman as Sol Pais, who allegedly traveled to Colorado on Monday night "and made threats in the Denver metropolitan area," the Jefferson County Sheriff's Office said on Facebook. 

Officials didn't provide further details about the threats or say where Pais was from, but they did say she was considered armed and extremely dangerous. 

"We are currently investigating what appears to be a credible threat possibly involving the schools," the Jefferson County Sheriff's Office said in a tweet. "Children are safe. Deputies are at the schools. "

Among the schools targeted in the threat was Columbine High School, where on  April 20,1999, two students, Dylan Klebold, 17, and Eric Harris, 18, killed 13 people and wounded 24, before killing themselves.

Since then, threats of violence have become a painful fact of everyday life for the school. On one day in December, the school received two threats, one caller claimed bombs had been planted inside Columbine High School and another reported a man with a gun. Neither was found.

As the anniversary nears, officials say they have seen an increase in threats toward the school, as well as an onslaught of curiosity seekers who trespass on school grounds, sometimes dozens per day.