"I thank the current members of the command staff for their years of service to this department, and look forward to working with them in different roles as we move this organization forward," Cummings said in a statement.
Assistant Chief David Yamahata, a 35-year veteran, was promoted to chief deputy of emergency operations, replacing Frazeur.
Assistant Chief Daren Palacios, a 31-year veteran, was promoted to chief deputy of administrative operations, replacing Mack.
Assistant Chief Roxanne Bercik, a 28-year veteran, was promoted to deputy chief of training and support bureau, replacing Fox.
"They all have had exemplary records within the organization and are considered visionaries for the future of the LAFD and the city of Los Angeles," Cummings said.
The move comes after Angelenos last March voted to amend the City Charter to exempt the Fire Department's deputy chiefs from civil service protections, allowing the fire chief to select his own staff.
"The new chief is spreading his wings and setting up the Fire Department the way he thinks it'll run best for him," said Pat McOsker, president of the firefighters union.
McClatchy-Tribune News Service