The B.C. Nurses' Union says it's concerned about a COVID-19 outbreak at the Abbotsford Regional Hospital.

Health Minister Adrian Dix and Provincial Health Officer Dr. Bonnie Henry announced the outbreak Friday afternoon.

BCNU president Christine Sorensen says four of its members working in the intensive care unit have tested positive for the virus.

Earlier in the day the union said two health care workers in the emergency department had also tested positive, but Fraser Health has clarified that the outbreak is confined to the ICU and includes six staff and two patients.

Sorensen said the outbreak is "extremely concerning." The nurses' union is working with the Fraser Health Authority and WorkSafeBC to investigate the cause of the outbreak, she said.

Nurses have limited access to personal protective equipment like face masks during their shifts, Sorensen said, adding that union members at the hospital are feeling anxious about their safety and the health of their colleagues.

Fraser Health says there is no evidence of a PPE breach during patient care at the hospital, and there isn't a shortage of PPE there.

The health authority says preliminary results of its investigation show that "vigilance is required in non-patient care areas."

"Enhanced precautions and infection prevention and control measures were implemented immediately and prior to the outbreak being declared," a spokesperson said in a written statement.

Abbotsford Regional Hospital is one of several health care centres across B.C. that is dedicated to treating people infected with COVID-19.

The province says a total of 15 long-term care or assisted-living facilities and five acute-care units have active cases in B.C.