Evanston Township High School was evacuated about 8:45 this morning after school officials received what police are calling "a non-specific threat to the safety of the occupants of the school, indicating that everyone would die at 9:06."
The school's roughly 3,000 students were ordered out of the building.
Deputy Police Chief Joe Bellino says high school staff accompanied by city police officers re-entered the building about 9:25 a.m. to conduct a systematic search, which turned up no visible threat.
Students were allowed to return to the building about 10 a.m.
A police investigation into the incident is underway.