TORONTO -- An outbreak has been declared at a North York school after two students tested positive for COVID-19.

During the city's coronavirus briefing, Dr. Eileen de Villa, the city's medical officer of health, said that the outbreak at Glen Park Public School, in the area of Englemount Avenue and Glengrove Avenue West, is the first outbreak declared at a Toronto school.

She said both students are isolating to recover from the infection.

In addition, a teacher and 35 students from two class cohorts have been sent home to self-isolate for 14 days. Parents in the school have been notified.

"One of the realities of living in a world with COVID-19 is that there will be cases in schools," de Villa said.

"I expect there will be similar announcements in future, and you can be confident the steps developed to manage the situation and reduce the risk of spread will be followed."

De Villa said an outbreak is declared when there are at least two confirmed cases of COVID-19 within a 14-day period, and at least one case was acquired in the school, which is a definition set by the province.

According to the Toronto District School Board, there are more than 30 schools with confirmed cases of COVID-19 as of Friday evening.

When asked why an outbreak has not been declared at Richview Collegiate Institute in Etobicoke, where there are three confirmed cases, de Villa said it is possible that those cases were not linked to the school and acquired elsewhere.

"The point of declaring an outbreak in any situation, whether it's a school or any other institution, is to actually allow for a swift response and to bring the resources to bear, to bring the infectious disease outbreak under control," de Villa said.

"That's really what the point of declaring the outbreak is, is to make sure that you're marshalling all the resources that are necessary, that the appropriate attention is paid to the circumstances so that we can manage the risk and reduce transmission."

Toronto Public Health reported 236 new infections on Friday, bringing the city's total to 18 363. Of those cases, 1,178 have died of the virus, while 15,725 have recovered.

"An increase day over day of this scale is a warning to the entire city," de Villa said.

"Wherever you live, wherever daily life takes you, you must take the steps for self-protection."