Some families were detained under the bridge for as long as four days, the A.C.L.U. said, adding that families with infant children were told to sleep on the ground and were not provided with any bedding, mats or chairs.
“We are demanding an immediate investigation by the inspector general into abuses inflicted on asylum seekers by Border Patrol agents in the outdoor facilities,” said Shaw Drake, policy counsel for the A.C.L.U.’s border rights center.
Migrants have since been transferred to undisclosed locations, he said, adding that “the agency has not told us or members of Congress where migrants are now being held and under what conditions.”
Local political leaders and human rights groups said that a sharp increase in asylum seekers should have been foreseeable, as part of an annual surge in border crossings before the arrival of the deadly summer heat.
Immigration officials were already scrambling to respond to a shifting profile of migrants arriving at the border with Mexico. Border Patrol apprehensions remain well below their peak of 1.6 million in 2000, but they have been climbing lately, reaching 467,000 in 2018, the highest figure in six years. And more of them are now Central American families seeking asylum rather than single men from Mexico.
Federal immigration officials claim that legal rulings have created loopholes that make it more attractive for Central Americans to apply for asylum in the United States.
“This status quo is not an option,” Andrew Meehan, assistant commissioner for public affairs at Customs and Border Protection, said in a statement on Saturday. “The legal framework must be addressed,” he said, repeating the administration’s calls for Congress to address asylum laws. “The only remedy to this crisis is congressional action.”