This stems from the Rampart Division Gang Units' corruption scandal that rocked the LAPD in the late 1990s.
LAPD Police Chief Charlie Beck said about four or five of the gang unit officers are filling out the forms and remaining with the detail.
Some residents in troubled neighborhoods said they hope the gang units remain intact and not shrink in their numbers.
In a written statement, the police officers' union, the Los Angeles Police Protective League, said they are very unhappy that the city's poorly thought out decision to implement the financial disclosure mandate might very well result in Los Angeles residents being deprived of having committed and experienced officers in gang units.
The deadline to submit financial disclosure forms for current gang unit officers is the end of March. Early notifications give the department time to train officers to fill in the vacancies.
The Associated Press contributed to this report.