MINNEAPOLIS (WCCO) – Minneapolis South High School has been placed on lockdown over an unspecified concern, according to school officials.

The building is under a “code yellow” lockdown, which increases the level of school security both inside and outside the building.

Officials said they were unable to explain the exact nature of the “concern” that led to the lockdown. The investigation is ongoing.

Parents were notified of the lockdown, and the school campus was closed during the lunch period.