(CNN) — A group of Haitian migrants is suing the Biden administration over its treatment of migrants, recounting in detail squalid conditions at a makeshift camp in Del Rio, Texas, this year and confrontations with officers on horseback, according to a lawsuit filed Monday.

In September, an influx of migrants — primarily Haitian — caught the Biden administration flatfooted, resulting in thousands amassing under the Del Rio International Bridge waiting to claim asylum. During that time, images of Border Patrol agents on horseback aggressively confronting migrants drew swift condemnation from advocates, lawmakers, and senior administration officials who pledged to investigate the incident.

Monday’s lawsuit provides first-hand accounts from migrants who had been in the encampment and had been confronted by Border Patrol, with one plaintiff saying she was “terrorized by officers on horseback.”

Mirard Joseph, a plaintiff in the case, said he watched his family suffer from hunger and dehydration while waiting at the makeshift camp under the Del Rio International Bridge in September. He decided to cross into Mexico to buy food and water, but upon returning, he encountered a mounted officer.

“After Mirard stepped out of the river, holding two bags of food for Madeleine and his daughter, he encountered a mounted officer. As other officers looked on—some on foot, others on horseback or in official vehicles—the mounted officer shouted at Mirard, lashed at him with split reins, grabbed his neck, and held his collar,” the lawsuit states.

“For several minutes, the officer attempted to drag Mirard back to the river, destroying Mirard’s shirt and causing his shoes to fall off in the process. The officer released Mirard only when the horse was about to trample him,” it continues.

Customs and Border Protection’s Office of Professional Responsibility is investigating the horse patrol incident caught in photos and videos. The office has reviewed videos and photographs and interviewed witnesses, employees and CBP leadership.

Monday’s lawsuit was filed in the US District Court for the District of Columbia. It includes accounts from 11 Haitian asylum seekers, all of whom say they fled dangerous conditions in Haiti and in South America where some of those in the complaint had been living prior to coming to the United States.

They are being represented by immigrant advocate organizations, including Innovation Law Lab, the Haitian Bridge Alliance and Justice Action Center.

Esther, another of the plaintiffs, said she was “terrorized by officers on horseback” when she tried to cross the river to find food for her baby, according to the complaint. Migrants staying at the camp had been going back and forth between the US and Mexico for resources amid a lack of adequate food and water.

Joseph and his family were ultimately expelled to Haiti under a Trump-era public health order, known as Title 42, that allows for the swift removal of migrants. The Biden administration has leaned on the order to expel tens of thousands of migrants including many of those who had been under the Del Rio International Bridge.

Monday’s lawsuit states that the Title 42 process “has been brutally deployed against Haitians.” It also claims that the Department of Homeland Security violated the rights of thousands of Haitian migrants in Del Rio, alleging that the administration knew there would be an increase of Haitians seeking asylum.

“Despite these warnings, the White House and DHS Defendants decided to take no action to plan for the arrival of these asylum seekers,” the complaint says.

CNN has reached out to DHS for comment.

For months, the Biden administration has wrestled with an unprecedented number of migrants crossing into the US, many of whom are fleeing deteriorating conditions in their home countries that have been exacerbated by the coronavirus pandemic.

CBP made 173,620 arrests in November, a 5% jump from the previous month and the first increase since the summer, when apprehensions began to drop, according to agency data.

The-CNN-Wire™ & © 2021 Cable News Network, Inc., a Time Warner Company. All rights reserved.

Join our Newsletter for the latest news right to your inbox