Update at 2 p.m.

MOUNT ZION, Ill. (WCIA) — Mt. Zion Police said the response at the town’s high school Monday morning was caused by concerns that a gun was inside the building.

Officials said in a press release on Facebook that a cardboard box displaying a gun manufacturer’s logo was found inside the high school; inside the box was a gun safety lock, paperwork and a serial number for a small-caliber handgun. Officers were dispatched to the school to assist in a cautionary lockdown and building search.

The box was discovered just before 7 a.m., as students were arriving. No students were inside the building at the time and those who had arrived were directed to the football field, where they waited until school officials allowed them to go home.

School administrators and Mt. Zion Police began searching the entire Mt. Zion High School and Junior High complex, assisted by the Macon County Sheriff’s Office and the Illinois Secretary of State Police. The latter agency providing K9s trained to search for explosives and firearms.

The search was unable to locate a gun.

There were no specific threats made toward the school, police officials said. They are now investigating how the box was left at the school and if a gun was in fact brought into the building.

Anyone who knows something about this incident is asked to contact Mt. Zion Police at 217-684-4012.

MOUNT ZION, Ill. (WCIA) — Students at Mount Zion High School are being sent home early amidst a police response at the school Monday morning.

Reporters on the scene saw multiple unmarked police cars at the school and K9 officers being led around the outside of the building. The officers left the school shortly before noon.

Mount Zion Police and school administrators did not respond to reporters’ requests for comment.

This is a developing story, and this article will be updated as we learn more.