"We saw mothers with infants and fathers with infants and small children, many of them listless, many were sick"

The memory was brief but vivid:

“The 1st sounds we heard before we could see the children held at Ursula were haunting cries of babies & toddlers,” Rep. Jackie Speier of California wrote on Twitter on Sunday.

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She and more than a dozen other Democratic lawmakers had inspected the migrant processing center known as Ursula in McAllen, Texas, earlier that day. What they witnessed, she tells PEOPLE, was a scene of sickness and filth at one of several border sites that have come under scrutiny amid an ongoing furor about the conditions in which migrants are being held.

Critics say President Donald Trump has fostered a culture of inhumanity toward immigrants — evident not just in his restrictions on those who can enter the country but in how government officials treat those in custody. Immigration officials, however, say they are being “overwhelmed” by the number of people crossing the border and are doing their best.

Congress recently passed a multi-billion-dollar aid bill while the president continues to demand Democratic lawmakers, who were swept to power in last year’s midterms, cede to his demands on tightening immigration law, which was one of his key campaign promises.

Speier, 69, says that among the children in Ursula center on Sunday was a boy, 8, who had been there alone for weeks after being taken from his 25-year-old sister.

“We saw mothers with infants and fathers with infants and small children, many of them listless, many were sick,” she tells PEOPLE. “They had this kind of vacant look on their faces.”

Men at another processing station nearby, so crowded that they could only stand, had been held up to 60 days with no showers or toothbrushes and they had been given no information on what to do while pleading with lawmakers to contact their families, according to Speier.

She also saw teen boys separated at the border from younger siblings who had no idea where their brothers and sisters were. They were disoriented from living in a place where the overhead lights never stopped shining.

“Imagine a facility where criminals in our federal prison system are treated better than they are — that a dog kennel like that would be shut down,” Speier says.

She recalls “the anguished faces,” she says.

“All those faces.”

Asked for comment, a spokesman for U.S. Customs and Border Protection, which oversees these facilities, referred PEOPLE to a tweet last week from the agency:

“For months, CBP leadership has spoken about the current border security & humanitarian crisis at the border. They’ve testified before Congress. They’ve been interviewed by the press. Months later, the influx of illegal crossings continues to overwhelm CBP resources.”

Speier tells PEOPLE this was the first time House members were allowed to bring in their phones to the border facilities. “A picture is worth a thousand words,” she says of her tweets, which went viral, “and I wanted to give the American people a visual, raw look at what’s going on.”

According to Speier, border patrol agents told the lawmakers they could not find anyone to take the minors at Ursula who were caring for young children. But Speier, who previously visited the facility last year, disputes this, noting that one 16-year-old girl caring for her baby there has a mother in New York she could join.

“Why are we keeping this 16-year-old, with an infant, in a prison for all intents and purposes?” she says.

Speier’s account is one of many about the conditions inside the border facilities, which are typically kept from public view but have been opened up to Congress and the media amid the national controversy.

CBS News recently also toured the Ursula station — the first time TV news cameras had been let in. Acting Secretary of Homeland Security Kevin McAleenan “made the decision to take the risk in bringing cameras in to be transparent about what we’re facing,” he told CBS.

Several migrant children have died in government custody in the last year.

In early July, pediatricians released pictures drawn by migrant children in government custody, to illustrate the trauma the kids were suffering.

It costs an estimated $300 to $700 per day per migrant at these facilities. When asked where the money is going, Speier says the cost is for operators who are allowed to charge an “extraordinary amount.”

“It makes no sense when so many of these people have sponsors, why aren’t we processing them and allowing them to go to their sponsors?” Speier says, referring to people connected to migrants who essentially vouch for them in order for the migrant to leave government custody pending the outcome of their immigration cases.

“We expect them to pay their air travel or bus ticket,” Speier says. “And we can easily pay for their bus ticket with one day’s housing now spent on them, put an ankle monitor on them, give them a court date for their asylum hearing and stop running this massive inhumane operation.”

“The only way we are going to get accountability,” she continues, “is through the courts.”

Speier expects to introduce legislation in the next few weeks with some of her colleagues who visited the facilities to help provide improved health care for the migrants.