LOS ANGELES (AP) — Nearly all inmates have been transferred out of a troubled women’s prison set to be shut down in California, and U.S. senators on Wednesday demanded an accounting of the rapid closure plan for the facility where sexual abuse by guards was rampant.

As of Tuesday only “a small group” of women were still being held at FCI Dublin, with the majority of its 605 inmates having been sent this week to other federal facilities, said Donald Murphy, a spokesperson for the Bureau of Prisons, or BOP. The unspecified number who remained at the minimum security prison near Oakland were pending release or transfer to halfway houses, he said.

Members of the Senate Judiciary Committee sent a letter to the BOP expressing concern over claims of a chaotic transfer process during which inmates on buses and planes didn’t receive proper medical care and were reportedly subjected to “mistreatment, harassment, neglect, and abuse while in transit.”