KITCHENER -- Four more students have tested positive for COVID-19 in the Region of Waterloo.

One case, which is in a student at Preston High School, was added to the Waterloo Region District School Board's COVID-19 case tracker on Tuesday afternoon.

Track every case of COVID-19 at a Waterloo Region school on our COVID-19 tracker.

A notice on the school's website said the student was last at the school on Sept. 16.

Anyone who is considered a high-risk contact will be contacted by public health officials, the notice said. Contacts in the identified cohort and some additional bus riders have been directed to self-isolate until at least Sept. 30.

Public health officials also confirmed two students had tested positive for COVID-19 at Cameron Heights Collegiate Institute on Sept. 22. The school board said the students haven't been at school since Sept. 16. The school said there are no high-risk contacts identified at the school.

There is also a confirmed case at Forest Hill Public School. There are no high-risk school contacts associated with that case, and the student hadn't been at school since Sept. 14.

The WRDSB reported four students with confirmed COVID-19 cases on Monday.

Region of Waterloo Public Health officials reported 29 new cases on Tuesday. There are currently 142 active cases in the region.

Provincially, Ontario recorded its highest single-day case increase since May, reporting 478 new COVID-19 cases.