An area school was placed under lockdown today after a bullet was found in a school bus. LaSalle County Sheriff Tom Templeton says deputies were notified that a single 22 caliber round was found in the rear of a bus during a cleaning. As a precaution, officials placed Waltham North and Waltham South schools on a soft lockdown. Both schools were searched, but nothing else was found and classes were resumed. Authorities say they are still investigating.