The lockdown at Estherville Lincoln Central Middle School was lifted at noon on Thursday and students returned to their normal schedules.
The school in Estherville, Iowa was put on lockdown earlier in the morning. School officials there told KEYC News 12 that the lockdown was implemented because a handgun cartridge was found. They did not specify whether the cartridge was spent. They also stressed that no gun has been found at the school.
Police were called in to investigate.
The district says more information is forthcoming regarding the situation.