The Dallas Police Department is about to undergo one of the largest shake-ups the department has ever seen.

Chief Renee Hall is expected to announce today a reorganization of the entire department.

She recently announced she wants to significantly reduce the number of assistant chiefs and deputy chiefs.

WFAA has learned that all chiefs and majors have been told to come in starting at 7:30 a.m. Thursday morning to learn if they are keeping their rank or being demoted.

The department has lost more than 500 officers in the past year so the chief says less command staff is needed to operate the department.

Chief Hall officially started in early September. Some critics have told WFAA that’s not enough time for the chief to know the men and women who hold the top ranks.

Multiple members of the command staff say the chief rarely meets with them and some critics wonder what the rush is to change the structure of the department.