Two U.S. lawmakers have asked the Senate Judiciary Committee to hold an “urgent” hearing about the Trump administration’s decision to hold detained migrants — many of whom are seeking asylum — in federal prisons.

The request, sent Wednesday from California Democratic Sens. Adam Schiff and Alex Padilla, raised concerns about the treatment of the detainees, citing a letter from an unnamed prison employee who described conditions at the federal lockup in Los Angeles and blamed “fear of Donald Trump” for the “inhumane” situation.

“I am alarmed that the civil rights of these detainees are not being upheld,” the employee wrote in a two-page letter attached to the senators’ request. “They haven’t been charged or convicted and we are literally putting them in prison.”

A spokesman for Padilla’s office said the senator had not received any response from the Judiciary Committee.

A prison agency spokesman would confirm only that the Bureau of Prisons, or BOP, is housing some detained migrants, but did not address any of the concerns raised in the letter and directed all other questions to Immigration and Customs Enforcement, known as ICE.

The senators’ request — and the prison worker’s letter — come amid a push by the Trump administration to house more migrants in the troubled federal prison system, which is already responsible for housing roughly 150,000 inmates across 122 facilities.

Earlier this month, a leaked copy of an agreement between immigration officials and the prison agency’s acting director showed that several facilities have been earmarked to hold migrants — including prisons in Atlanta, Philadelphia, Miami and Leavenworth, Kan.

As The Times previously reported, the understaffed federal prison in Berlin, N.H., is also expecting to receive 500 detainees. In response, prison agency officials emailed staff at other facilities in search of volunteers from across the country willing to work at the rural New England lockup.

Emails sent from prison union leaders also show the Trump administration may be considering a plan to sent immigrants to the recently shuttered “rape club” federal prison in Dublin, Calif.

Amid those changes, immigration officials first sent several detainees to the federal prison in downtown Los Angeles in early February. Initially, as The Times previously reported, prison staff were unsure where to house the detainees or how best to keep them separate from other prisoners.

Eventually they put the men in their own unit within the facility, creating added work for the staff, who one official with knowledge of the situation said had “no guidance” on how to handle migrants differently from typical federal prisoners. (The official asked not to be named, as they were not authorized to speak publicly about the matter.)

Last weekend, immigration officials sent 12 more migrants to the downtown L.A. facility after a much-anticipated ICE sweep across the county.

The prison employee’s letter this week described the first arrivals at the Metropolitan Detention Center in Los Angeles on Feb. 2, when ICE agents “dropped off buses” of detainees. Because the detainees aren’t regular inmates, the prison worker said, they can’t be entered into the system to use the phones or contact their families.

“Employees have been told that they can’t turn them away and have to make room to house them. We have not been trained or employed for this purpose, and we don’t know what these individuals are being detained for,” the letter said. “BOP resources are being used to shuttle detainees, which is not where our limited resources should be going.”

The letter went on to detail problems that arose during the first Trump administration, when detainees were sent to a federal prison in Victorville.

“There were reports of detainees receiving insufficient medical care, employees stretched thin and working overtime, and instances of violence resulting from a lack of adequate staff resources,” the letter said. “There were threats of suicide by some detainees, several of whom were reportedly exercising their legal right to seek asylum in this country.”

This time around, the prison employee said, there was no reason to expect anything different, as the agency continues to struggle with staffing shortages.

“It seems like both fear of Donald Trump and the need for revenue are driving these decisions. But the bottom line is that BOP employees did not sign up for this,” the employee wrote. “This abuse of resources and of my colleagues seems to be for nothing more than political gain.”