Nelson Mandela High School in Calgary was placed on watch status Tuesday by the province, meaning that school's COVID-19 outbreak has reached five or more cases that were likely acquired or transmitted in the school.
Two other Calgary-area schools, St. Wilfrid and Canyon Meadows, remain on watch status as well as one in Airdrie.
There are outbreaks at 14 other Calgary schools defined by two or more cases.
Alberta reported 276 new cases of COVID-19 Tuesday, including 78 in the Calgary zone.
There were 11 additional workers put into isolation at Foothills hospital, and no new confirmed cases of COVID-19 to report.