OTTAWA -- The top doctor at the Renfrew County and District Health Unit is blaming a visitor from a locked down part of Ontario for a COVID-19 outbreak at a Pembroke dentist's office.

The RCDHU sent a media release on Sunday confirming three staff at the unidentified office had tested positive for COVID-19.

"Two confirmed cases that are linked within the organization meets the provincial guideline for the declaration of a workplace outbreak," the RCDHU said. "RCDHU is working closely with the Pembroke dental office to ensure necessary measures continue to be in place to protect all staff and the public."

In the release, the acting medical officer of health for the region, Dr. Robert Cushman, blamed someone from a locked down part of Ontario for bringing the virus to Pembroke.

“This was another travel-related situation where a visitor had come from a grey area currently in lockdown," Dr. Cushman said. "I am reminding everyone that this year it is imperative that the holidays be spent at home with members of your immediate household. Non-essential travel must be suspended.”

The RCDHU says all close contacts of the affected individuals at the dentist's office have been told to self-isolate and arrange to be tested for COVID-19.

"Patients who are considered to be at low risk, are being contacted by the dental office with instructions to self-monitor and if symptoms develop, to call the Renfrew County Virtual Triage Assessment Centre (RC VTAC) at 1-844-727-6404 to book an appointment for testing," the health unit's release said.

The RCDHU is currently in the "Green-Prevent" zone, the lowest level under the province's framework. It is the only health region in eastern Ontario in the green zone. All other eastern Ontario health units are in either the "Yellow-Protect" or "Orange-Restrict" levels.

Toronto, York Region, Peel Region, and Windsor-Essex are in the "Grey-Lockdown" zone, the highest level of restrictions, and Hamilton will be moved to lockdown on Monday.