Classes were dismissed early at Littlefield High School because a threat written in pencil on a bathroom door.
Littlefield Police Chief Thomas Esparza says the message indicated there was a bomb in the school. Superintendent Jerry Blakely says the building was evacuated at about 10:30. Classes were later dismissed for the day as further precaution.
A bomb dog unit from Lubbock conducted a search. No explosives were found.
Investigators ask anyone with information about the source of the threat to report it to police.