Congressional Democrats on Tuesday blasted conditions at an immigrant detention center in Homestead, Florida, following a second-straight day of inspecting the government facilities, calling the shelter a "warehouse of children for profit."

Rep. Elijah Cummings, the chairman of the House Committee on Oversight and Reform, scheduled a hearing on the separation and treatment of immigrant children, inviting acting Secretary Kevin McAleenan from the Department of Homeland Security and acting Commissioner Mark Morgan from U.S. Customs and Border Protection to appear July 12 while signaling he is prepared to subpoena senior Trump officials if they do not accept his invitation to testify.

"The Trump Administration's actions at the southern border are grotesque and dehumanizing," Cummings, D-Md., noted. "There seems to be open contempt for the rule of law and for basic human decency. The Committee needs to hear directly from the heads of these agencies as soon as possible in light of the almost daily reports of abuse and defiance. I encourage Acting Secretary McAleenan and Acting Commissioner Morgan to appear voluntarily in order to answer these critical questions."

The hearing will also examine a secret Facebook group where current and former border patrol agents purportedly posted "racist, sexist and xenophobic" material disparaging members of Congress and immigrants.

On Monday, other lawmakers traveled to the Texas-Mexico border where they alleged mistreatment of migrants detained in El Paso and Clint, Texas.

After that visit, New York Democratic Rep. Alexandria Ocasio-Cortez said women at one border patrol station were told to drink out of toilets, saying the sinks used for drinking water were broken. On "Fox and Friends" Tuesday morning, one of President Donald Trump's senior advisers, Kellyanne Conway, called her a "liar."

Later Tuesday, an administration official told ABC News that at least one of the sinks was broken, but agents had put jugs of water nearby for the women to drink.

At the facilities, toilets are connected to sinks and Ocasio-Cortez retweeted a photo she said looked similar to the toilet she saw.

In the Tuesday visit in Florida, Rep. Bennie Thompson, the chairman of the House Committee on Homeland Security, joined a delegation of Democrats at the Homestead Temporary Shelter for Unaccompanied Children, where several Democratic presidential candidates visited while they were in town for the Democratic presidential debate last week.

"It's what I didn't see that bothers me the most," Thompson, D-Miss., told reporters, expressing concern that the Miami-Dade school system was not involved in the education of immigrants while lamenting that U.S. taxpayers pay $775 per day, per child. "It doesn't matter what the president or any of his people say, we're going to get it right."

After the tour, Georgia Democrat Rep. John Lewis, a civil rights icon, said the experience reinforced his deepest beliefs.

"I came here to learn. I've been deeply moved by what I have seen and what I have heard," Lewis said. "When you see something that's not right, not fair, not just, you have to say something. You have to do something."

Lawmakers also expressed disgust over a secret Facebook group where current and former border agents purportedly shared lewd content disparaging members of the delegation ahead of their visit. The group was named "I'm 10-15" -- the Border Patrol's code for "aliens in custody."

Rep. Frederica Wilson, a Florida Democrat, led the delegation and marked her third trip to the facility, called the behavior "a disgrace" and called on any border patrol personnel who posted inappropriate content to be prosecuted.

"You cannot intimidate members of Congress," Wilson, D-Florida, said. "It is against the law."

Rep. Jahana Hayes, a freshman Democrat who was recognized as the the 2016 Teacher of the Year, said the delegation was shown empty dormitory rooms with neatly-made beds. She bemoaned that Health and Human Services, which operates the shelter, "just missed out on an opportunity to ask Congress for help."

"It was too perfect," Hayes, D-Mass., said. "What I saw in there is not anything I'd want for my children. It's not okay for anyone else's children."

This cannot exist," she continued. "God help us all if this is what Americans do. God help us all."

Earlier Tuesday, Ocasio-Cortez charged that the border patrol agents present were disrespectful of Members of Congress present for the tour, even snapping photos.

Ocasio-Cortez and other Democratic Latina lawmakers, including Reps. Veronica Escobar of Texas and Nanette Barragan and Pete Aguilar of California were heckled after their tour Monday, with protesters shouting "liar," "Trump 2020," "do your job," and "B.S." as the members detailed their experience.

"The country has gone into dark place," Escobar said, telling reporters it was the 10th congressional delegation she had led since taking office in January.

While it's unclear whether any of the agents who encountered lawmakers Monday had posted any content on the Facebook page, progressives questioned the wisdom of passing a $4.6 billion bill to continue facilitating operations at the facilities – even though the package also included money earmarked for humanitarian relief.

"We are appalled by the vile and inexcusable conduct displayed in this Facebook group. Clearly, there is a pervasive culture within CBP of dehumanizing and racist behavior towards immigrants in custody, by some CBP agents," Congressional Progressive Caucus Co-Chairs Mark Pocan and Pramila Jayapal wrote in a statement. "This disturbing report underscores our concerns with the decision to provide additional funding for CBP absent appropriate and necessary safeguards to ensure detained immigrants are treated with dignity. We support a full investigation into this despicable conduct and we urge CBP to take swift disciplinary action against the perpetrators, up to and including termination."

Facebook told ABC News that it is cooperating with federal authorities looking into the group.

"We want everyone using Facebook to feel safe," a Facebook spokesperson told ABC. "Our Community Standards apply across Facebook, including in secret Groups. We're cooperating with federal authorities in their investigation."