A new report by Reveal from The Center for Investigative Reporting found that the U.S. government operates “secret shelters” to detain some unaccompanied migrant minors. The facilities, which are outside of the regular Office of Refugee Resettlement network, reportedly specialize in housing youth with mental or behavioral challenges. The practice may be in violation of a long-standing agreement that says the government must provide lawyers with accurate information on the whereabouts of all children in their care. It’s unknown how many such sites exist, but Reveal identified at least five locations, where at least 16 immigrant youths are detained, some as young as 9 years old. At least one of the facilities has previously been accused of numerous violations, including sexual and physical abuse.