Employees of the largest housing provider for unaccompanied migrant children in the U.S. have repeatedly sexually abused and harassed children in their care over the past eight years, the Justice Department alleges.

Southwest Key employees, including supervisors, have raped, touched or solicited sex and nude images of children since at least 2015, the DOJ alleged in a lawsuit filed Wednesday. At least two employees have been charged since 2020, according to the lawsuit.

Based in Austin, Southwest Key is the largest provider of housing for unaccompanied migrant children, operating under grants from the U.S. Department of Health and Human Services. It has 29 child migrant shelters — 17 in Texas, 10 in Arizona and two in California — with room for 6,350 children. The company's largest shelter in Brownsville has a capacity of 1,200.

The Associated Press left a message with the company seeking comment Thursday.

HHS reported 7,762 children at all of its contracted facilities on May 31, according to the most recent data on its website, which does not break the numbers down by shelter or provider. The department declined to say how many children are in Southwest Key's care or if the agency continues to assign children to its care.

The lawsuit, which provided details of some of the alleged abuse, asserts that authorities received more than 100 reports of sexual abuse or harassment at the provider's shelters since 2015.

Among the suit's allegations: An employee "repeatedly sexually abused" three girls ages 5, 8 and 11 at the Casa Franklin shelter in El Paso, Texas. The 8-year-old told investigators that the worker "repeatedly entered their bedrooms in the middle of the night to touch their 'private area,' and he threatened to kill their families if they disclosed the abuse."

The suit also alleges that an employee of the provider's shelter in Tucson, Arizona, took an 11-year-old boy to a hotel and paid him to perform sexual acts for several days in 2020.

Children were threatened with violence against themselves or their families if they reported the abuse, according to the lawsuit. It added that testimony from the victims revealed staff in some instances knew about the abuse and failed to report it or concealed it.

HHS Secretary Xavier Becerra said Thursday that the complaint "raises serious pattern or practice concerns" about Southwest Key. "HHS has a zero-tolerance policy for all forms of sexual abuse, sexual harassment, inappropriate sexual behavior and discrimination," he said in a statement.

The lawsuit comes less than three weeks after a federal judge granted the Justice Department's request to lift special court oversight of HHS's care of unaccompanied migrant children. President Joe Biden's administration argued that new safeguards rendered special oversight unnecessary 27 years after it began.