Mason City authorities say they are talking to a person of interest who may have caused a school lockdown with a report of a gun on campus.
Mason County Sheriff's Sgt. John Windsor says about 800 students at Illini Central High School and adjacent elementary and junior high schools were locked in classrooms Wednesday, after a caller made the report.
Some students say they had to wait in their classroom for about two hours before being walked with their hands up out of the school.
In a statement, Illini Central Superintendent Lori Harrison said the "potential threat" forced a four-hour lockdown which ended after the Mason City school was deemed secure.
Police Chief Michael Schoo wouldn't identify the person of interest investigators are talking to.