Gov. Maura Healey formally seized St. Elizabeth's Medical Center in Brighton Friday, according to a statement released by her office. The move will allow patients to keep receiving care at St. Elizabeth's before Boston Medical Center becomes its official owner, Healey's office said. More than 60 patients are currently staying at the Brighton hospital for various treatments. Healey had announced plans in mid-August to take control of the property through eminent domain to keep the hospital open as a deal proceeded to transfer its ownership from bankrupt Steward Health Care to a new operator, Boston Medical Center.