ST. CHARLES, Ill. (CBS/WBBM) – The discovery of a single bullet Thursday morning at St. Charles North High School prompted school officials to dismiss students early and to keep their backpacks overnight for inspection.

A staff member found the round of live ammunition in a common area of the building at about 9:30 a.m., and students were sent home shortly after noon, school officials said.

READ MORE: Employee At FOUND Hotel In River North Accused Of Stabbing Man, Going Into Rage, Leaving Guests In Terror

No threats were made in connection with the discovery of the bullet, and no weapons were found after a search of the building, St. Charles police said. However, students were instructed to leave their backpacks at the school and only take personal items, like keys, wallets and cell phones with them. 

District 303 Superintendent Don Schlomann says the inspection of bags would go on late into the night.  In the initial screening, authorities would use an X-ray “wand” to see if anything shows up.

READ MORE: Chicago Weather: Weekend Warmup

“We’ll tag those backpacks and set them aside, keep them secure and then open them in the presence of the student tomorrow,” Schlomann said.

Officiasl said an ATF dog trained to detect live ammunition would also be deployed. The screening process is expected to be a tedious process because 2,000 students attend the school.

MORE NEWS: Hundreds Of Cars Roll Through Downtown For Second Night To Celebrate Mexican Independence Day

LISTEN: WBBM Newsradio’s Bob Roberts reports