About 500 migrant children of the 2,300 who were separated from their parents at the U.S. border with Mexico have been reunited since May, officials with Department of Homeland Security told NBC News and The Associated Press on Friday.

It was unclear how many of the roughly 500 children were still being detained with their families. Federal agencies were working to set up a centralized reunification process for the remaining separated children and their families at the Port Isabel Detention Center, just north of border in Texas, a DHS official told the AP.

Still, confusion over how migrant families would be handled continued to mount as questions swirled over the treatment of detained children in Virginia and Texas.

"Trump's order leaves us with more questions than answers: How to ensure kids are safely returned to parents? When? Where are they being held? In what conditions? What care are they getting?" Sen. Tim Kaine, D-Va., tweeted Thursday.

The Trump administration had not previously said how many children may have been reunited with their families, but parents have shared stories of not knowing where their children are for weeks and one former Immigration and Customs Enforcement official told NBC News that some separations may be permanent.

Kaine, meanwhile, said that he will seek more information into an Associated Press report that said immigrant children at the Shenandoah Valley Juvenile Center in Staunton, Virginia, were allegedly bound, beaten and isolated in solitary confinement. Six Latino teens made sworn statements about the abuse they say took place between 2015 and 2018, under both the Obama and Trump administrations.

The details were shared as part of a federal class-action lawsuit.

"We need to see these kids, and we need answers about what's going on at this facility," Sen. Mark Warner, D-Va., tweeted in response to the report.

Here are the latest developments:

After President Donald Trump signed an executive order that keeps families together at the border, House leaders postponed a vote Thursday on a broad immigration bill. The Senate remains divided on the issue as well, and Trump tweeted Friday morning that "even if we get 100% Republican votes in the Senate, we need 10 Democrat votes to get a much needed Immigration Bill" and added that "Republicans should stop wasting their time on Immigration until after we elect more Senators and Congressmen/women in November." He also tweeted in reference to undocumented immigrants that "Democrats tell their phony stories of sadness and grief, hoping it will help them in the elections."

The Justice Department urged a federal judge Thursday to allow the government to detain migrant families for longer than 20 days, a move meant to keep children with their parents instead of them being placed in a separate facility for minors.

Immigration rights activists and lawyers are warning that Trump's executive order could actually create new problems for migrant kids, and they say it did nothing to address the other ways the administration has been making things harder for children who are brought into the United States illegally.

First lady Melania Trump caused a stir on social media Thursday when she wore a jacket with the phrase "I REALLY DON'T CARE, DO U?" on the back in white graffiti-styled text. The first lady was going to the border to visit migrant children, and critics say the coat's cryptic message was in poor taste. But President Trump tweeted that it was meant as a jab to the media.

The family separations have prompted outrage and a slew of donations. One fundraiser, a Facebook campaign started by a Silicon Valley couple, had raised more than $18.2 million as of Friday morning. Earlier this week, Facebook confirmed that the fundraiser, which at one point was raking in $4,000 a minute, is the largest single fundraiser in the social network’s history.

United Nations experts are denouncing Trump's executive order, and said it "may lead to indefinite detention of entire families in violation of international human rights standards," according to a statement from the U.N. Human Rights' Office of the High Commissioner.

Attorney General Jeff Sessions first announced last month that the government would criminally prosecute anyone who crosses the U.S.-Mexico border illegally — known as a "zero-tolerance" policy.

With the outrage over the family separations, there were signs that the administration was dialing back its policy — but also still confusion.

The federal public defender's office for the region that covers cases from El Paso to San Antonio said Thursday that the U.S. Attorney's Office would be dismissing cases in which parents were charged with illegally entering or re-entering the country and were subsequently separated from their children.

"Going forward, they will no longer bring criminal charges against a parent or parents entering the United States if they have their child with them," wrote Maureen Scott Franco, the federal public defender for the Western District of Texas, in an email shown to the AP.

But less than an hour later, Daryl Fields, a U.S. Attorney's Office spokesman, retracted the statement.

"As part of that transition, the office today dismissed certain cases that were pending when the President issued the order," Fields said. "Contrary to reporting, the office did not issue any memorandum to the courts."