EAST CHICAGO, Ind. (CBS) — An elementary school building in East Chicago Indiana has been closed after several staff members tested positive for COVID-19.

In a letter issued Tuesday, McKinley Elementary School Principal Dr. Rasheeda Green said the school will be closed until Monday, Aug. 24. A thorough cleaning is under way.

Students in the School City of East Chicago district is already learning remotely, but the staff who tested positive will also now be teaching remotely.

“I want to reiterate that at McKinley Elementary our staff and student safety is a priority! I want to share that we are actively taking precautions to prevent the introduction and spread of the Coronavirus and other germs,” Green wrote. “The status of this situation is extremely fluid, and we are monitoring the progress of this matter thoroughly and consistently.”

ZIP code data shows East Chicago is the hardest-hit town in Lake County, Indiana when it comes to the coronavirus. A total of 2.5% of residents have tested positive, for a total of 729 cases.