PETAWAWA, ONT. -- Hundreds of soldiers based at CFB Petawawa are in quarantine after a large training exercise resulted in numerous positive COVID-19 cases.

The training course, which took place Nov. 13 and 14 in Petawawa, Ont., has turned up at least seven positive cases in soldiers so far and three positive cases in civilian family members of soldiers.

"When a positive case was identified that person was sent into isolation and then we did contact tracing," says Col. Eric Landry, Commander of 2 Canadian Mechanized Brigade Group. "Everybody who was in close contact with that person was asked to quarantine."

The training involved 373 soldiers working closely together outdoors, as well as another 100 people operating at a greater distance back.

Landry says everyone who participated in the exercise was double vaccinated.

"(They were) operating at a platoon level, at a company level," Landry explains to CTV News Ottawa. "So these large groups of people, they need to work at that level in order to meet our NATO requirements. These cannot be achieved by having soldiers work individually; they have to work as a group. This is why we enforce all these force protection health measures."

The Renfrew County and District Health Unit is also following 10 high-risk contacts in the community, and monitoring another three soldiers showing symptoms. Acting Medical Officer of Health Dr. Robert Cushman expects to see more positive cases and is worried about the spread to the greater community.

"The numbers are large when you factor in the civilian dependents," says Dr. Cushman. "We're talking about approaching a thousand people quite easily."

Everyone involved in the training exercise will stay in either isolation if they are showing symptoms or quarantine if they are asymptomatic until Nov. 22. At that time, all 373 CAF members will be tested again and the situation will be re-evaluated.

"Everybody in the brigade who was not comfortable going back home to their own household were offered quarters on base," says Landry.

Dr. Cushman says the training exercise was stopped part way through the weekend given the revelation of the outbreak, which was key to slowing the spread. He also says he has no issues with the nature of the training exercise, given everyone involved was fully vaccinated and outdoors.

"The forces have lost some time so clearly they need to get back to work and training and preparation," says Dr. Cushman. "We're talking about 370 people in a field. We're not talking about 18,000 people at a hockey game."

Currently 92 per cent of those in 2 Canadian Mechanized Brigade Group at Garrison Petawawa are fully vaccination. Landry says the other eight per cent are having their files considered for employability.

"Hopefully, we'll get out of this by the middle of next week," adds the medical officer of health. "Hopefully, we can limit the spread."