MONTREAL -- More than 80 students in Quebec City are in isolation after three cases of COVID-19 were confirmed at two high schools, the local public health agency said Monday.

Two positive COVID-19 cases were detected at Polyvalente de Charlesbourg and one case was confirmed at Ecole Jean-de-Brebeuf, health agency spokesman Mathieu Boivin said in an email. He said 81 students from the two schools were told to isolate for 14 days beginning Aug. 28.

Boivin said the infected students are considered "community cases" because all three contracted COVID-19 outside school. He said the infections are not linked.

COVID-19 cases have been detected at a handful of schools across Quebec after most French-language schools resumed last week.

Quebec reported 140 new cases of COVID-19 and two additional deaths attributed to the novel coronavirus Monday, as classes resumed at the province's largest English-language public school board.

One of the deaths took place in the past 24 hours, while the other occurred between Aug. 24-29, health officials said in a news release.

Quebec Premier Francois Legault urged Quebecers to be vigilant after the recent uptick in COVID-19 infections. He said there was no single cause of the increase in daily cases.

"Above all -- above all -- I don't want to close schools," Legault told reporters in Montreal.

"Let's keep that in mind, we owe it to our children," he said. "We want our children to stay in schools, and so for our children to stay in schools, we have to be careful, we have to be disciplined, we have to respect all the instructions."

The English Montreal School Board said it would closely follow COVID-19 guidelines set by the provincial government as students returned to classes Monday morning. Students in Grade 4 and under are not required to wear face masks, while older students must wear them in common areas and on school transportation.

Students will still be able to take the bus to school, but health and safety guidelines only permit 44 students per bus instead of the typical 72. The board also asked for parents to drive or walk their children to school if they can.

In a newsletter to parents, the board said it has ordered medical equipment such as masks, hand sanitizer and disinfectant in "large quantities" for students. The school board said it won't accept donations of personal protective equipment in order to "maintain the control and quality."

Other English school boards, including Lester B. Pearson, Eastern Townships and Riverside, will also reopen their schools this week.

Meanwhile, a French-language school board said late Sunday two more teachers at a high school north of Montreal tested positive for COVID-19.

Four teachers at Polyvalente Deux-Montagnes have now tested positive after classes resumed last week, the school board, the Centre de services scolaire de la Seigneurie-des-Mille-Iles, said in a statement.

About 20 other staff members who were in contact with those cases were placed in isolation as a precaution. The public health agency in the Laurentians region said in an email that 12 students from the school will be told to isolate until Sept. 10.

The school board added that most Grade 10 and 11 Polyvalente Deux-Montagnes students who were sent home last week after the teachers tested positive were back in school Monday.

Quebec Health Minister Christian Dube also stressed Monday that Quebecers need to remain cautious if they want to prevent outbreaks in schools. The recent infections tied to schools occurred in the community, he said.

"It's not the school that is an issue," Dube said.

Richard Masse of Quebec's public health department said his office will begin to receive a daily update on the COVID-19 situation in schools beginning Tuesday. "We're investigating every case, every outbreak, and we intervene in the first 24 hours," Masse said.

Quebec has now reported 62,492 total cases of COVID-19 and 5,760 deaths since the pandemic began.

Hospitalizations dropped by four over the past 24 hours, for a total of 112. Of those, 18 people were in intensive care, an increase of two from the previous day.

This report by The Canadian Press was first published Aug. 31, 2020.