Toronto Public Health has declared a second outbreak of COVID-19 at an elementary school, this one resulting in the temporarily cancellation of all in-person classes and activities for a full week.

Three staff members and one student at Mason Road Junior Public School in Scarborough have now tested positive for the deadly coronavirus, according to the Toronto District School Board.

The board announced the news publicly on Sunday night, noting on Twitter that the school would be closed from Monday, September 28 until Friday, October 2, while public health officials continue their investigation.

A letter sent to Mason Road Junior Public School parents and guardians this weekend asked that all students and staff members self-isolate until October 2.

Additional cleaning is scheduled to take place while in-person classes are cancelled.

Important Update: @TOPublicHealth has declared an outbreak at Mason Road JPS & as a result has requested that it be temporarily closed Monday, September 28 to Friday, October 2, while they continue their investigation.

Information has already been shared with school community.

— Toronto District School Board (@tdsb) September 28, 2020

"I know news of an outbreak and school closure will, understandably, be worrisome for families," wrote the school's principal, Helen Wong, in a letter obtained by CityNews. 

"Please know that we are in constant contact with TPH and should they believe any additional communications or steps are required, we will let you know as soon as possible."

Mason Junior is the second Toronto school in which an official outbreak of COVID-19 has been declared. The first was at Glen Park Public School in North York, as declared on Friday afternoon.

Toronto Medical Officer of Health Dr. Eileen de Villa reinforced on Friday when announcing the first school that an outbreak is defined as "at least two confirmed cases of COVID-19 within a 14 day period, and with a link to a school setting." 

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

"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."