Kirkwood High School in suburban St. Louis is returning to normal after a lockdown prompted by what sounded like gunfire.
Police were called just before 6 a.m. Tuesday to the school after a call about possible shots fired and breaking glass. No students or teachers were in the building at the time.
Several officers responded and searched the building. Meanwhile, the Kirkwood School District advised parents to keep their kids away from the school.
Police searched for about two hours and found no evidence of gunfire but did find that a box of light bulbs had fallen, possibly causing a noise that sounded like gunfire.
By around 8 a.m., police declared an "all clear," allowing students, teachers and staff into the building.