(CNN)A group of 18 senators requested additional information about overcrowding at a border facility in a letter to acting Department of Homeland Security Secretary Kevin McAleenan Wednesday.
The letter stems from a May DHS inspector general report that found "dangerous overcrowding" and unsanitary conditions at an El Paso, Texas, Border Patrol processing facility following an unannounced inspection. The report's release in late May sparked outrage from lawmakers and illustrated the issues facing the Department of Homeland Security, primarily the challenge it faces in processing a growing number of migrants crossing the border.
"This is unacceptable and requires immediate action by DHS leadership to ensure that such situations never occur again," the senators -- led by Nevada's Democratic Sen. Jacky Rosen -- wrote in the letter, citing cells which held migrants over the maximum capacity.
The IG found "standing room only conditions" at the El Paso Del Norte Processing Center, which has a maximum capacity of 125 migrants. On May 7 and 8, logs indicated that there were "approximately 750 and 900 detainees, respectively."
"We also observed detainees standing on toilets in the cells to make room and gain breathing space, thus limiting access to the toilets," the report, which was first obtained by CNN, stated.
DHS and McAleenan have been flagging the rising number of migrants and crowded condition at border camps. Earlier this year, the Trump administration also requested additional funds from Congress, but that request has not been filled.
Rosen describes DHS' response to the report as "insufficient." The department had said in its response that it planned to construct additional structures to accommodate the influx of migrants.
"However, this does not provide an immediate solution to the dangerous overcrowding at El Paso Del Norte Processing Center," Rosen wrote. "We believe DHS must take immediate action to address this critical health and safety issue and other humanitarian conditions that threaten vulnerable populations, especially children."
The senators posed a series of questions in the letter, including how the department will alleviate the overcrowding at El Paso Del Norte Processing Center in the near future, whether it's processing migrants within the 72-hour rule, and how it's ensuring the health and safety of migrants.
The letter requests answers within 21 days.