Close to 100 Grade 10 students at a high school in Edmonton are self-isolating after someone from the school tested positive for COVID-19.

While it's unclear whether the person who tested positive for the virus was a student or staff member, Ross Sheppard High School is now one of four schools in the city where a COVID-19 case has been confirmed since in-person classes began last week. 

The Edmonton Public Schools division was informed of the positive test on Monday. 

"The school called impacted students. The students will be supported with learning while they are required to isolate at home. The school will provide more information to these families soon," a spokesperson told the Edmonton Journal, adding that the school already underwent a deep clean.

Also in Edmonton, cases of COVID-19 were confirmed at Archbishop MacDonald High School, Louis St. Laurent Junior/Senior High School, and École Sainte-Jeanne-d'Arc. 

The news comes as over 20 schools in the province of Alberta grapple with COVID-19 cases, according to a list compiled by the Support Our Students Alberta advocacy group. 

‼️ 25 & 26 ‼️

📚#ABEd SCHOOL COVID-19 TRACKER at 26📚

📚Notre Dame CSSD
📚Fort Saskatchewan High

Stay updated at https://t.co/yAz2HmCIR6 pic.twitter.com/2D1NmYC5Xp

— Support Our Students (@SOSAlberta) September 8, 2020

At a press conference on Tuesday, however, Alberta's chief medical officer of health, Dr. Deena Hinshaw, said that 11 cases in 11 different schools were reported to Alberta Public Health (AHS) but that the number could go up as the AHS count only includes those who attended the institution while they were considered infectious.

She added that cases in schools were not unexpected and the virus in these 11 instances was not acquired at school.

A # of cases in school staff & students were among those reported this weekend. In each case, AHS worked quickly w/school officials to identify cases & ensure anyone at risk is isolated to limit spread. This is crucial to keeping schools safe in the days & weeks ahead. (5/6)

— Dr. Deena Hinshaw (@CMOH_Alberta) September 8, 2020

"Getting told you have tested positive or are a close contact can be upsetting for these children and their parents. If your child is a close contact, they will need to isolate for 14 days," Hinshaw said.

"I know that it can be frustrating after just a few days in school that they already may need to stay home for two weeks if they are a close contact."

There are currently 1,692 active cases in Alberta, the most the province has seen since May.