BOSTON — Massachusetts Gov. Charlie Baker announced Tuesday he will activate up to 500 members of the National Guard to support understaffed hospitals across the state facing a surge of COVID-19 patients and to bolster non-emergency medical transportation needs.

Up to 300 Guard members will begin training this week to provide nonclinical support at 55 acute care hospitals and 12 ambulance service providers, the state Executive Office of Health and Human Services said in a statement. They will be deployed Dec. 27.

The goal is to ensure that hospitals have sufficient capacity to care for both COVID-19 and non-COVID-19 patients.

The Guard members will provide support in five critical areas identified by hospitals and ambulance services: non-emergency transportion between health care facilities; observing patients at risk for harming themselves; security and helping to maintain a safe workplace; moving patients within hospitals, such as bringing them from their rooms to tests; and delivering meals to patients in their rooms.

In addition, the state Department of Public Health on Tuesday directed all hospitals effective Dec. 27 to postpone or cancel all nonessential elective procedures likely to result in admission.

The state's health care system faces a staffing shortage that has contributed to the loss of about 500 medical/surgical and ICU hospital beds this year, at a time when patient levels are on the rise, the office said.

Massachusetts also updated its masking advisory, recommending that everyone, regardless of vaccination status, wear a face covering in indoor, public spaces.