New York Rep. Alexandria Ocasio-Cortez said she observed a pattern of "systemic cruelty" at detention centers for migrants during a trip to a facilities in Texas on Monday, accusing Border Patrol officers of holding women in cells with no running water and instructing them to drink out of toilets.

The freshman Democrat, a vocal critic of the Trump administration's hardline immigration agenda, made the stunning accusations after visiting a Customs and Border Protection (CBP) station in El Paso with a group of other Democratic lawmakers.

"This has been horrifying so far. It is hard to understate the enormity of the problem," Ocasio-Cortez wrote on Twitter. "We're talking systemic cruelty (with) a dehumanizing culture that treats them like animals."

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She said CBP officers laughed at members of Congress during the visit to the El Paso facility. According to the congresswoman, one migrant woman told her that officers waged "psychological warfare" against the detainees by waking them up at "odd hours for no reason" and calling them profanities.

"There's abuse in these facilities," Ocasio-Cortez told reporters outside the facility. "This was them knowing a congressional visit was coming. This was CBP on their best behavior. Telling people to drink out of the toilet."

After a visit to a migrant detention facility in El Paso, Texas, Rep. Alexandria Ocasio-Cortez spoke on what she says is happening inside.https://t.co/CpmH73SMkn pic.twitter.com/CpmjAztm3n — CBS4Local (@CBS4Local) July 1, 2019

CBP, which oversees Border Patrol officers, did not immediately respond to a request for comment on the congresswoman's allegations.

The congressional visit came hours after ProPublica revealed that members of a private Facebook group for current and former Border Patrol officers made insensitive comments about the deaths of migrants and posted sexist jokes about Latina lawmakers. Among the posts were vulgar illustrations portraying Ocasio-Cortez engaging in sexual acts with President Trump and a detained migrant, according to ProPublica.

CBP said it has opened an internal investigation and informed the Department of Homeland Security's inspector general of the report. Border Patrol chief Carla Provost called the social media posts "inappropriate" and contrary to the values of her agency. "Any employees found to have violated our standards of conduct will be held accountable," she added.

After her visit to the CBP station in El Paso, Ocasio-Cortez and other members of the Congressional Hispanic Caucus visited the Border Patrol facility at Clint, in the outskirts of El Paso. The station there has come under severe scrutiny after independent monitors reported learning of unsanitary, crowded — and what one lawyer called "inhumane" — living conditions for detained migrant children.

According to the attorneys who inspected the facility, older children were taking care of the younger ones. Some young mothers had to wear clothes stained with breast milk. The children also did not have access to soap and toothbrushes, and most had not showered since they crossed the southern border.

In a press conference after the visit, Democratic lawmakers continued to denounce the conditions they witnessed inside both facilities. Texas Rep. Joaquin Castro, the chair of the Congressional Hispanic Caucus, also said a detained migrant told him and other members of Congress that a CBP officer advised her to drink water out of the toilet.

"These are the conditions created by the Trump administration," Castro said as a group of hecklers yelled "liar!"

Rep. Joaquin Castro speaks alongside members of the Hispanic Caucus after touring inside of the Border Patrol station in Clint, Texas, Monday, July 1, 2019. Castro's identical twin, presidential candidate Julian Castro, held a rally outside the building over the weekend. Cedar Attanasio / AP

When it was Michigan Rep. Rashida Tlaib's turn to speak, a heckler shouted, "We don't want Sharia law here!" Tlaib is Muslim and has been the target of smears over her religion.

As she delivered impassioned remarks about seeing a group of migrant mothers weeping because they were separated from their children, Rep. Ayanna Pressley of Massachusetts confronted the hecklers directly.

"Keep yelling. This is very appropriate. Vile rhetoric for vile actions. Hateful rhetoric for hateful behavior. Racist words and venom for racist policies," she told them.

"Today we are lifting up these stories in the hopes that you will see the light," she added. "And if you don't, we will bring the fire."