Clean-up is underway at Gladbrook-Reinbeck Junior-Senior High School after a minor fire damaged part of the building on Thursday.

In a Facebook post, Superintendent David Hill said contractors doing roof replacement work inadvertently ignited a wooden structure surrounding a fourth-floor classroom window. Flames traveled alongside the window and spread about two feet into the classroom's true ceiling before the fire was put out. A third-floor classroom wall also sustained some minor water damage.

According to Hill, visible flames were initially controlled by roof workers using fire extinguishers until Reinbeck firefighters arrived to put the fire out. They also removed sections of the fourth-floor roof and classroom wall to access the damage and make sure the fire hadn't spread to other parts of the building (see photos below).

Photo By: Elwin Huffman - Townsquare Media

Hill said no one was in the fourth-floor classroom when the fire broke out, but an internship meeting involving some students was being held in the third-floor library and back-to-school registration was taking place in the first-floor cafeteria. When the fire alarm sounded, the building was evacuated and no one was injured.

Although the building has been cleared to re-enter, Hill confirmed that registration has been moved to the district's elementary school a few blocks away and will continue there through 6 PM Friday.

Hill said school operations will only be minimally affected by the fire and he expects them to be back to normal within a few days. A professional company was expected to be at the building on Friday, cleaning and sanitizing the damaged fourth-floor classroom.

The fire will not delay the start of classes later this month, Hill said. Gladbrook-Reinbeck students are scheduled to return to school on August 23.