CHICAGO (CBS)–Calumet City School District 155 shut down the district’s three schools Tuesday amid findings of mold detected in one of the buildings.

An email to the school district community from District 155 Superintendent Troy Paraday said mold was found at one of the schools–Wentworth Junior High.

The other two schools in the district, Woodrow Wilson Elementary and Wentworth Intermediate–are reopening on Wednesday, the district said. Wentworth Junior High will remain closed.

“The health and safety of all our students and staff is our highest priority,” according to the statement from the Superintent. “In that regard, it was brought to the District’s attention that mold may have been detected in the Wentworth Junior High Building. Once the concern became known, the District took immediate steps to assess the concern and this phase is ongoing. We take this matter very seriously and are committed to taking action to remediate the concern to preserve the highest standard for our learning environments.”