CALGARY -- Parents of students at Bowness High School in Calgary were informed late Saturday that a positive case of COVID-19 was confirmed at the institution, but officials say the school will remain open.

The Calgary Board of Education sent home a letter to parents letting them know about the case of the illness "diagnosed in an individual from Bowness High School."

Tara Orgill says her son is in a cohort group with a student who tested positive.

“It kind of threw me back,” she said. “At first I was a little pissed off about it, to be honest. I was angry. But now I’m just scared, I’m worried.”

Orgill said she received a call from 811 this weekend telling her that her son had to isolate.

The list of others also impacted — both students and staff — could be long.

A teacher tells CTV News students at Bowness High are in four different cohort groups, which are made up of up to 40 students each. Students also have a homeroom of roughly 25.

“The concentric circles start to build very quickly when you’re talking about that many people,” Support Our Students Executive Director Medeana Moussa said. “My initial reaction is I’m not overly surprised. (The province) could still invest more money and decrease class sizes to prevent further outbreaks.”

The letter sent to parents, written by school principal Jana Macdonald, states Bowness High will remain open to in-person classes and staff are "working closely with AHS" to ensure all precautions are being taken.

"This includes cleaning and disinfecting all items touched by the individual, and removing and storing items that cannot be cleaned and disinfected (paper, books, etc.,) in a sealed container for a minimum of 10 days. Our facilities staff has already enacted all cleaning protocols as directed by Environmental Public Health," Macdonald wrote.

It also said that only the parents or guardians of students, as well as any staff, visitors or volunteers who came into close contact with the confirmed case will be contacted directly by Alberta Health Services (AHS).

"All students directed to quarantine by AHS will be supported in maintaining course work during the designated period. Communication regarding this will be provided directly from the school to impacted students." 

The letter also reminded parents to monitor for any signs or symptoms of COVID-19 in their children and to go through Alberta Health's daily checklist every day before sending them to school.

"If you/your child has any of the symptoms of illness listed on the Alberta Health daily checklist, please fill out the online Alberta Health Services COVID-19 self-assessment or call Health Link at 811 and stay home/keep your child at home."

During Friday's COVID-19 update, Alberta's chief medical officer of health Dr. Deena Hinshaw stated it would not be unexpected to have positive cases at schools in Alberta.

"We did know there would be cases in school, just like we've identified cases in other workplaces and cases in other settings. We knew that because there is COVID circulating in the community and the school reflects the community, this is something that was going to happen."

Alberta Health is not sharing any details about the case at Bowness High School due to patient confidentiality, but confirmed it and that AHS is working with the school.

Hinshaw said public health officials are also maintaining close contact with school administrators so they know who to contact when a positive case is found.

"This is a part of our plans, this is a part of our response."