EL PASO — Congressional Democrats on Monday condemned postings made in a secret Facebook group for U.S. Border Patrol agents that targeted migrants and some prominent lawmakers with attacks that the chairman of the Congressional Hispanic Caucus called “vulgar, disgusting and vile.”

The posts sparked special outrage among a delegation of more than a dozen House members who had just started a tour of federal immigration facilities in Southwest Texas when ProPublica broke the story.

Some of the Facebook posts discussed throwing burritos at the visiting lawmakers, while others joked in profane language about the deaths of migrants and included a vulgar illustration of Rep. Alexandria Ocasio-Cortez (D-N.Y.) being forced to engage in a sexual act by President Trump, according to images of the posts obtained by ProPublica.

Before they toured two Border Patrol stations Monday, several members asked their hosts in a private briefing whether they would be safe inside, said Rep. Pete Aguilar (D-Calif.).

The airing of the private attacks, Aguilar said, made it even more difficult for congressional overseers to trust the Border Patrol as the federal government works to address the surge of migrants at the U.S.-Mexico border.

“It’s very tough to back them up when their active and retired members are part of this Facebook page,” he said in an interview. “Even if it’s a very small percentage, it’s unfortunate they harbor some very dark imagery and very dark thoughts about migrants and members of Congress.”

Border Patrol Chief Carla Provost, who responded to the ProPublica report, described the online group as “completely inappropriate and contrary to the honor and integrity I see — and expect — from our agents day in and day out” and she vowed to hold accountable any employee found to have violated the agency’s rules of conduct.

A separate statement from Customs and Border Protection, the patrol’s parent agency, said the inspector general of the Department of Homeland Security would conduct an independent investigation.

The Washington Post was not able to confirm the existence of the group, called “I’m 10-15,” after the law enforcement code for “aliens in custody,” as the group is not visible to people who aren’t members.

The lawmakers visited Border Patrol stations in El Paso and Clint, Tex., as well as a facility in El Paso for children operated by the Department of Health and Human Services. The Congressional Hispanic Caucus organized the trip after conditions at the Clint facility prompted an outcry last month, with lawyers who visited describing scenes of hundreds of sick and dirty children without their parents and inconsolable toddlers in the care of other children.

During Monday’s visit to Clint, lawmakers saw only about two dozen migrant children being held there, down from about 700 in May, Aguilar said. Members expressed more pointed concerns about the El Paso facility, where they said several hundred people are still detained.

They described a visit with a group of more than a dozen Cuban women housed in a crowded cell without running water who reported going weeks without showers.

Ocasio-Cortez said one woman said she was told by Border Patrol officers to drink out of a toilet. “And that was them knowing that a congressional visit was coming,” the visibly angry lawmaker said in an interview. “This is CBP on their best behavior, telling people to drink out of the toilet.”

Rep. Judy Chu (D-Calif.), another member of the delegation, echoed Ocasio-Cortez’s description in an account posted to Twitter and said the conditions at the facility were “appalling and disgusting.” Rep. Madeleine Dean (D-Pa.) called them indicative of a “human rights crisis.”

A Department of Homeland Security official, who was not authorized to discuss the visit and spoke on the condition of anonymity, insisted that no Border Patrol agent would make a migrant in their custody drink from a toilet and said there was water available.

Aguilar and others said the revelations surrounding the Facebook group — which came to light during the morning visit to the HHS facility — colored the visits later in the day to the Border Patrol sites.

“It shocks the conscience that these agents are entrusted with the lives of anybody in their custody, much less vulnerable people,” said Rep. Joaquin Castro (D-Tex.), the caucus’s chairman. “And the vulgar xenophobia and sexism is clearly pervasive.”

Rep. Veronica Escobar (D), who represents the El Paso area, wondered to reporters how many current Border Patrol members and supervisors belonged to the group and tolerated the rhetoric on display there: “Anyone who views vulnerable human lives in this way should have absolutely no access to a badge or a gun,” she said.

Castro told reporters in Clint that lawmakers will investigate the Facebook posts.

House Homeland Security Chairman Bennie G. Thompson (D-Miss.), who did not participate in Monday’s border visits, said in a statement that the Facebook group is “truly abhorrent and shameful” and that those who participated in the attacks “seem empowered by President Trump and seem all too willing to take his anti-immigrant rhetoric to the next level when they think no one is watching.”

As the furor over the posts mounted, Trump supporters gathered outside the Clint detention center while the Democrats were inside. At a news conference afterward, the lawmakers struggled to be heard as protesters shouted them down.

“Build a wall; deport ’em all,” one shouted. “That’s the way we get rid of this problem!”

When Rep. Rashida Tlaib (D-Mich.), one of three Muslim members of Congress, stood at the event, a protester shouted: “We care about Jesus Christ. We don’t care about Sharia law.”

“I will outlove your hate,” Tlaib replied, choked with emotion. “You can all scream at me. I will never stop speaking truth to power.”

The visit came just days after a bitterly divided House approved $4.6 billion in emergency aid for the border. Liberal Democrats, many of whom made the trip to Texas, wanted strict limits on how Trump could spend the money.

Other Democrats were intent on getting the money to the administration as quickly as possible, agreeing to a measure that would pump billions of dollars into the budgets of agencies, including the Department of Health and Human Services, that have been overwhelmed by the influx of Central American migrants at the border.

In an interview last week, Trump defended conditions at migrant detention facilities during his tenure. “No, the conditions are much better than they were under President Obama,” he told the Hill newspaper.