Officials in Oxford confirmed Sacco's passing Sunday afternoon, according to WGME.
The Portland Fire Department said they responded to the Spring Street parking garage at 9:50 a.m. Sunday for a reported medical incident and transported the patient to Maine Medical Center.
Sacco was hired as fire chief in June 2017. He had previously retired as New Gloucester's fire chief in 2016 after 12 years with the department.
Sacco was New Gloucester's first full time fire chief.
Governor Janet Mills released a statement about Sacco's passing.
“Our hearts, already broken by the loss of Captain Joel Barnes, also mourn the loss of Oxford Fire Chief Gary Sacco," she said. "In a testament to his own character, Chief Sacco lost his life while honoring that of his fallen brother, fellow firefighter Captain Barnes.
"I join with people across Maine in offering my thoughts and prayers to Chief Sacco’s family and friends, the Oxford Fire Department, and all of Maine’s first responders. The state of Maine has given two of its best to the Heavens," the governor said.