"We are concerned that overcrowding and prolonged detention represent an immediate risk to the health and safety of DHS agents and officers, and to those detained," they wrote.
In its response to the report, the Department of Homeland Security says the surge of migrants crossing the Southern border has led to an "acute and worsening crisis."
"The current migration flow and the resulting humanitarian crisis are rapidly overwhelming the ability of the Federal Government to respond," DHS says.
Bay Area congresswoman Zoe Lofgren, D-San Jose, said she and congressman Jerry Nadler, D-N.Y., are asking individuals with the DHS Office of the Inspector General to testify before the House Judiciary Committee.
"The first thing we hope to do — and I spoke to Jerry Nadler, the chairman, earlier today — is to have the Inspector General in to go through the full report with the judiciary committee," said Lofgren, who chairs the House Judiciary Committee's subcommittee on immigration and citizenship.
"We need to hold the departments to account," Lofgren said. “What they are doing violates their requirements under the law. And they have to stop.”
In May, according to DHS, an average of more than 4,600 people a day crossed illegally or arrived at ports of entry without the proper documents, compared to less than 700 a day in the same period two years ago.
DHS says Customs and Border Protection facilities are at "peak capacity" and that the agency is adding detention capacity at three tent facilities in order to improve the conditions for migrants. CBP also says it "continues to take steps to address the health and safety of those in custody," including by expanding medical services.