 The successor to Davis, Daryl F. Gates, came into office just as Proposition 13 reduced the department's budget, cutting police numbers to less than 7,000 in seven years, just as drug and gang crime reached unprecedented highs.To combat the rising tide of gang-related violence, Gates introduced Operation Hammer in 1987, which resulted in an unprecedented number of arrests, mostly of black American and Hispanic youths.Gates retired in 1992, just after the Rodney King-related 1992 Los Angeles riots in April and May and the damaging Christopher Commission Report, and was replaced by Willie L. Williams, the fiftieth chief, the first African-American officer to hold the office and the first non-internal appointee for almost 40 years.