Alton High School was evacuated Tuesday afternoon after a threatening message was found inside the school, according the police.
Madison County Sheriff's Department School Resource Officer assigned to Alton High was informed by a faculty member at the school that a written message of a threatening nature was located within the school.
The school's administration was notified, and the school was evacuated. Deputies from the Madison County Sheriff's Department conducted a search but found nothing in the school.
Then, students were allowed to reenter and classes resumed.
Police continue to investigate.