TORONTO -- A North York high school is temporarily shutting down due to a COVID-19 outbreak, the Toronto District School Board says.

In a tweet Tuesday night, the TDSB said that Marc Garneau Collegiate Institute in the Thorncliffe area will be closed as of Wednesday.

“@TOPublicHealth has advised that, based on the current situation at Marc Garneau CI, all students & staff will be dismissed beginning tomorrow up to & including Friday, December 18 to allow TPH time to finish investigation & conduct additional COVID-19 testing,” the TDSB said in its tweet.

According to provincial data, 10 students have tested positive for the virus at the school. However TDSB Spokesperson Ryan Bird told CP24 Tuesday night that Toronto Public Health has found that there are in fact 14 active student cases at the school so far.

“Their investigation is now continuing to see exactly how those cases are being transmitted. So to allow them time to complete their investigation, and to conduct more COVID-19 testing, they are now recommending that the students and staff be dismissed,” Bird said.

He said school-wide testing for COVID-19 was set to begin on Thursday, but will now be rescheduled.

A number of schools in the Thorncliffe area have been dealing with COVID-019 outbreaks, including Thorncliffe Park Public School, which was set to reopen as early as Thursday.

With more students having recently tested positive, it’s not clear whether that will happen this week. Bird said the number of confirmed COVID-19 cases at the school now stands at 29.

“We're awaiting additional information from Toronto Public Health,” he said. “That closure, or essentially dismissal, was supposed to end after the end of the day tomorrow. But we're waiting for some more information to see if that will be extended or if it will indeed open on Thursday.”

Bird said it remains to be seen whether testing will go ahead in some form for Marc Garneau CI students. A letter was sent out to parents Tuesday night to inform them of the early dismissal.

“We want people to know that we are working very closely with Toronto Public Health, to make sure that we're giving them all the up-to-date information as we get it,” he said. “We want to pass that along to not only our families but our staff to make sure they're up to date on everything that's happening at school.”

Because the temporary closure period overlaps with winter break, the school will not reopen before Jan. 4, Bird said.