Florida’s child-welfare agency has investigated six cases of alleged child sexual abuse at a federal migrant shelter in South Florida in less than a year, The News Service of Florida reports. The cases include allegations against caregivers looking after migrant children. The shelter in question, Homestead temporary migrant children’s shelter, was reopened by the federal government last March as part of Trump’s “zero-tolerance” policy. Since then, the Florida Department of Children and Families has investigated six sexual-abuse claims at the facility. Investigators later said there were no “indicators” of abuse, but some lawmakers remain concerned. “Knowing what we know about children in vulnerable situations, the only conclusion we can make is that this is the tip of the iceberg because we know there’s under-reporting,” said state Sen. Jose Javier Rodriguez.

The U.S. Department of Health and Human Services, which oversees the contractor that runs Homestead, said any allegations of sexual abuse involving federal staff results in immediate removal from duties that give the staff members access to children. The federal agency declined to comment on the six cases reported at Homestead.