Two children in Ontario under the age of 10 have died after testing positive for COVID-19 in the past two weeks, health officials say.

The deaths include a child under the age of four in Toronto and a child under the age of 10 in Wellington County, the respective local public health units said.

The circumstances surrounding both deaths are still not known. 

"We offer our condolences as we confirm a recent COVID-19-related death of a child in Toronto," Toronto Public Health told CTV News Toronto in a statement Thursday, adding they are unable to provide further details due to privacy reasons. 

Wellington-Dufferin-Guelph Public Health also issued a statement Thursday confirming a girl under the age of 10 had died with COVID-19. They were unable to confirm the child's cause of death.

"Our region has now experienced its first death of a child with the virus," Medical Officer of Health Dr. Nicole Mercer said. "No words are sufficient to comfort those grieving this terrible loss. In this tragic moment, I offer my deepest condolences on behalf of everyone at Public Health to the family."

It remains rare for children to get seriously ill after contracting COVID-19. 

Since the start of the COVID-19 pandemic, nine children have died in Ontario after testing positive for COVID-19. 

Chief Medical Officer of Health Dr. Kieran Moore said Thursday he is “taken aback” by the news of the deaths, but added the "death of children is exceptionally rare from this virus."

"My heart goes out to the family and to the friends. And I hope we give the family privacy to grieve," Moore said. 

He said Ontario currently has "only got a handful of children in intensive care units" who are testing positive for COVID-19.

"Obviously it is just awful to hear about the death of anyone, especially when we hear about a death in a younger individual. Tragic," Dr. Isaac Bogoch, an infectious diseases specialist with Toronto General Hospital, said Thursday morning.

"We still know that COVID in general doesn't cause as severe illness in kids as it does in adults but that doesn't mean it can't happen. And sadly, we are starting to see more and more of these cases of kids getting sick enough to land in hospital and some rare but still very serious reports of kids succumbing to this illness. This is very likely just going to be a reflection of how significant and how much community transmission there is."