The Thunder Bay District Health Unit says it is investigating an outbreak of COVID-19 associated with a mine near Marathon, Ont.

The health unit has identified three people with COVID-19 associated with a specific work area at the Barrick Hemlo Williams gold mine, according to a Thursday news release issued by the health unit.

It is working closely with management to determine whether any other workers were exposed and to identify and follow up on any contacts outside of the mine.

"The mine has already undertaken many measures to reduce any spread of the virus at the mine site. These are currently being enhanced and reinforced, and the mine has communicated these enhancements to its employees, contractors, the community and First Nation partners," the health unit said in the release. "Further measures will be taken as needed to manage this situation."

Individuals identified as close contacts have been contacted directly by a public health nurse and provided instructions about what they need to do, the health unit said.

It considers anyone who is not specifically contacted by public health to be at low risk at this time.

If the investigation identifies additional close contacts, they will also be contacted directly by a public health nurse, the health unit said.

Earlier this year, an outbreak at the Lac Des Iles mine in northwestern Ontario was responsible for 25 cases of COVID-19, including one death.