Columbine High School in Littleton is back to normal operations after a lockout was lifted around noon Monday.
The lockout at Columbine High School has been lifted.— Jeffco PublicSchools (@JeffcoSchoolsCo) September 22, 2014
Earlier in the day, no one was allowed to leave the school after it received a threat. Melissa Reeves, news media specialist for Jefferson County Schools, wouldn't tell CPR News the nature of the threat.
The Jefferson County Sheriff’s office is investigating.