LOS ANGELES — Sheriff's deputies in two desert cities northeast of Los Angeles unlawfully targeted blacks living in public housing, subjecting them to unnecessary stops and seizures and using unnecessary force even when people were handcuffed, the U.S. Justice Department announced Friday after a two-year investigation.

Federal authorities released the findings of a two-year investigation into the Sheriff's Department's Lancaster and Palmdale stations in Mojave Desert, about 70 miles north of Los Angeles. The report was in response to complaints made by some minority residents who moved to the area and said they were met with discrimination by law enforcement and government officials.

The report found the nation's largest sheriff's department engaged in a "pattern of unreasonable force" and investigated only one misconduct complaint out of 180 made by residents over a one-year period. Despite the findings, federal officials were encouraged by the response from Sheriff Lee Baca.

"While our investigation showed significant problems in LASD's Antelope Valley stations, we are confident that we will be able to reach an agreement that will provide meaningful and sustainable reform," said Roy Austin Jr., deputy assistant attorney general.

Baca disagrees with the report's conclusions, but has instituted reforms to improve the department, said Steve Whitmore, a department spokesman.

"We stand resolute that we have not discriminated against members of the public," Whitmore said. "We haven't seen any racial profiling."

The discrimination issue in the Antelope Valley has been simmering for years as the demographics shifted from primarily white to black and Latino. Blacks and Hispanics account for more than two-thirds of the city of Palmdale's roughly 150,000 residents, according to census statistics. The Antelope Valley also had the highest rate of hate crimes of any other area in Los Angeles County as of 2010, federal officials said.

Federal officials said black and Latino residents were more likely to be stopped and searched than other ethnicities, but were often released without being cited. Sheriff's deputies also unnecessarily put African-Americans in the backseat of their patrol cars for minor offenses, a violation of the Fourth Amendment.

In one instance, a domestic violence victim was placed in a patrol car, which agitated the suspect and let to both a physical struggle between the man and deputies and the victim getting pepper-sprayed because she also grew upset.

"Unjustified backseat detentions contribute to tension and diminished trust between Antelope Valley deputies and the community," federal officials wrote.

Sheriff's deputies also harassed and intimidated blacks and others during enforcement of a housing voucher program. Sometimes as many as nine deputies would accompany housing investigators during checks and would often have their guns drawn, federal officials said.

"The sheer number of armed, uniformed deputies who participated in many of the compliance checks call into question whether voucher holders were able to give meaningful consent," to inspections, according to the report.

The government and Los Angeles County have reached preliminary agreements to make broad changes to policing in the Antelope Valley and to enforcement of the housing voucher plan. Some of the reforms include revising training and use-of-force policies as well as participating in community meetings to gauge feedback from residents.

Whitmore said the department now has an exhaustive process to determine whether deputies need to come out during inspections. Deputies also carry complaint forms when they are on patrol. The forms are also available at the front desk of the two stations.

Baca has served four terms as sheriff and was named as the nation's Sheriff of the Year earlier this year by the National Sheriff's Association. Baca has been criticized for alleged misconduct by his deputies in the jails. The FBI is investigating.

The department's actions in the Antelope Valley have been scrutinized before. A July 2010 report by the nonprofit Police Assessment Resource Center found deputies were more likely to use force against minorities during an obstruction arrest than against whites.

The NAACP and the Community Action League also filed a lawsuit in 2011 accusing the cities of Palmdale and Lancaster of racial discrimination at low-income housing projects.