Rep. Joaquin Castro of Texas released videos purportedly showing the conditions inside two migrant detention centers along the border with Mexico.

Castro, the chairman of the Congressional Hispanic Caucus, led a delegation of more than a dozen Democratic lawmakers to tour the U.S. Customs and Border Protection facilities in southwest Texas on Monday. The delegation was told to "surrender their phones" ahead of the tour, Rep. Alexandria Ocasio-Cortez of New York wrote on Twitter. But Castro "was able to get a device in," Ocasio-Cortez tweeted.

At a border patrol station in El Paso, the congressional members met with a group of women in custody there who agreed to be filmed and gave their names, according to a senior aide in Castro's office.

Castro posted the video on his Twitter account purportedly showing the women, who he said were all from Cuba, sitting in sleeping bags on a concrete floor of a small cell, which he said had a toilet but no running water to drink from or to wash their hands.

"Many said they had not bathed for 15 days," Castro tweeted. "Some had been separated from children, some had been held for more than 50 days. Several complained they had not received their medications, including one for epilepsy."

Next, the delegation toured a border patrol station in Clint, which Castro said houses children and some parents. Castro posted a video on Twitter purportedly showing the mobile shower units there, which he described as "dank, dirty" and "small in number for the hundreds of people there just a few weeks ago."

Castro also recounted seeing a young boy in custody at the facility who smiled and "pressed his face against the dirty glass of a locked steel door," trying to talk to them through the thick glass.

Ahead of the delegation's visit to the detention centers, members of a private Facebook group reportedly populated by current and former Customs and Border Protection agents made jokes about migrant deaths, posted derogatory comments about Hispanic lawmakers and shared a lewd meme depicting Ocasio-Cortez. The existence of the secret group was exposed in a ProPublica story on Monday morning.

Ocasio-Cortez claimed on Twitter that, during the tour, she "caught officers trying to sneak photos, laughing."

"Imagine how they treat the women trapped inside," she tweeted.

The U.S. Border Patrol has since launched an investigation into whether its personnel participated in the "disturbing social media activity." Facebook said it is cooperating in the probe.

"These posts are completely inappropriate and contrary to the honor and integrity I see -- and expect -- from our agents day in and day out," Border Patrol Chief Carla Provost said in a statement Monday. "Any employees found to have violated our standards of conduct will be held accountable."

ABC News' Anne Flaherty, John Parkinson, Quinn Owen and Marissa Parra contributed to this report.