Dietrich High School was placed on lockdown after an African-American woman reportedly forced her way into the building, according to officials with the Lincoln County Sheriff's Office.
The woman has been located at a nearby home following the incident but officers have not said if they made an arrest.
No word on why the woman is in the building.
Families of Dietrich school students are being asked to meet at the local LDS temple.
The incident comes hours after national attention was directed at the high school following a high-profile rape and lawsuit case. The district is reporting that they have had over 100 calls regarding the alleged rape of a football player.