An O'Fallon Township High School student was arrested Wednesday afternoon at the school after bomb making materials were discovered at his home, according to O'Fallon Police Chief John Betten.
Betten said four other individuals are also being detained at the O'Fallon Police Department in connection with this case.
The Illinois Secretary of State Police bomb squad was at a home at 904 Scott-Troy Road in O'Fallon Wednesday afternoon along with about a dozen FBI agents.
FBI spokesman Brad Ware said it is too early in the investigation to release additional information.
FBI agents with a bomb-sniffing dog combed through a shed on the property. The agents also removed computer equipment from the home.
The names of the individuals arrested were not released pending formal charges.
Neighbors said they did not know the residents well enough to comment.
As a precaution, the OTHS Smiley Campus was locked down for an hour and 15 minutes Wednesday afternoon, Betten said.
O'Fallon School District 203 Superintendent Darcy Benway said the school was locked down as a precaution related to an off-campus incident, and students and employees were safely secured in their classrooms and the cafeteria.
"St. Clair County law enforcement discovered hazardous materials at the residence of an OTHS student. As a precautionary measure, the OTHS Smiley campus was thoroughly checked," Benway said. "There was no known threat made to any student or to OTHS, again, this was a precautionary security check. The OTHS administration will always err on the side of caution as the safety of students and employees is our top priority."
During the lockdown, O'Fallon Police in collaboration with the Scott Air Force Base K-9 team escorted bomb sniffing dogs through the building and nothing was found on campus, according to Benway.
She said parents and staff members received both email and telephone notifications throughout the lockdown.
Contact reporter Jamie Forsythe at 239-2562 or email@example.com.