The U.S. Supreme Court ordered the Trump administration early Saturday to temporarily halt the deportations of dozens of alleged Venezuelan gang members who immigration advocates say were at imminent risk of being removed from the country.

“The Government is directed not to remove any member of the putative class of detainees from the United States until further order of this Court,” the order reads.

The court did not explain its reasoning in its brief, unsigned emergency order. Justices Clarence Thomas and Samuel A. Alito Jr. dissented, with Alito saying he would file a more fulsome statement on his disagreement with the ruling later.

The Trump administration was preparing to deport the Venezuelan men under the Alien Enemies Act, the American Civil Liberties Union said Friday as it scrambled to find a court it could persuade to step in and block the removals before it was too late.

In a statement early Saturday, the ACLU’s lead counsel in the case, Lee Gelernt, said the organization was “relieved that the Supreme Court has not permitted the administration to whisk them away the way others were just last month.”

But the fate of the detainees targeted for this latest round of removals remains unresolved. Attorneys for the migrants had also pressed federal judges in Texas and Washington as well as the New Orleans-based U.S. Court of Appeals for the 5th Circuit to intervene, arguing that the government had not provided those targeted a meaningful opportunity to challenge the reasons for their removals.

In its order early Saturday, the Supreme Court said it would take further action after the 5th Circuit had weighed in and asked the solicitor general to respond to the ACLU’s claim. Around that same time, a three-judge panel from that appellate court denied the ACLU’s emergency request to block the deportations and chided its lawyers for coming to them before a lower court had ruled on the issue.

The ACLU has maintained time is of the essence as several migrants at an immigration detention center in North Texas had received written notices of removal over the past several days, and a second group of an unknown number was told to get ready for travel Friday. Their lawyers told the justices that many of those individuals had already been loaded onto buses presumably headed to the airport and had been informed that they might be removed from the United States as soon as Friday afternoon or Saturday.

Their attorneys said that without a court order blocking the removals, dozens or hundreds of proposed class members “may be removed to a possible life sentence in El Salvador with no real opportunity to contest their designation or removal.”

Copies of those notices received by the migrants, filed in court, were written only in English and said the recipient had been “determined to be an Alien Enemy” and would be deported. Aside from stating that the recipient can “make a phone call,” the notices do not inform those who receive them when they will be deported, that they are entitled to contest their removal, or outline the means for doing so, the ACLU said.

“There’s no box to check to say I want to contest,” Gelernt said during a hastily convened hearing Friday evening in federal court in Washington, one of the districts where the ACLU sought unsuccessfully to press its case. “There’s nothing that says there is a right to contest, much less the time frame.”

Justice Department lawyer Drew Ensign told the court that the government had no plans to fly any of the targeted migrants out of the country Friday night but “reserve[d] the right” to begin them as soon as Saturday.

He maintained that officials need only provide 24 hours’ notice to targeted individuals and were not required to instruct them on how to contest deportation decisions.

Georgetown Law professor Steve Vladeck called the Supreme Court’s intervention overnight aggressive and “a sign that a majority of the justices have lost their patience with the procedural games being played by the Trump administration,” at least as it relates to the cases involving the Alien Enemies Act.

Vladeck said it was telling that the justices chose not to wait for a ruling from the 5th Circuit to block further deportations, underscoring, he wrote in his newsletter Saturday, “how seriously the court, or at least the majority of it, took the urgency of the matter.”

Aziz Z. Huq, a constitutional law scholar at the University of Chicago, cautioned against reading too much into the interim order from the Supreme Court filed early Saturday. The brief order does not address the underlying legal questions about Trump’s authority to use the wartime powers statute to deport alleged gang members, he noted.

But Huq said the message in the court’s order is consistent with its earlier directives that the administration must allow for notice and due process when pursuing deportations. Trump officials have dragged their feet in following directives from the justices and lower-court judges in the case of Kilmar Abrego Garcia, a Maryland man wrongly deported last month.

The fact that the Trump administration has taken such a hard-line position against correcting that error, Huq said, “may be working against them in this case.” He said at least some of the justices, in acting urgently overnight to pause any deportations, may have in the back of their minds that “the Trump administration has demonstrated when there are mistakes, they won’t correct them.”

Trump’s use of the Alien Enemies Act, a rarely invoked wartime statute, is at the center of an escalating standoff between his administration and the courts. His administration deported more than 130 Venezuelans under the Alien Enemies Act on March 15. The government has since sent two more flights carrying migrants to El Salvador, but none of those men were deported under the wartime authority.

Earlier this month, the Supreme Court ruled that the Trump administration had the authority to deport migrants under the act but said the government must first provide detainees an opportunity to contest their removals. Those challenges, the justices said, should be brought in the court districts nearest to the detention centers where the migrants are being held. That set off a flurry of activity in federal courts across the country as immigration advocates seek to locate and identify migrants targeted for removal and quickly file individual cases on their behalf in front of multiple federal courts.

In one of its court filings Friday, the ACLU said that “officers last night told class members that they will be removed within 24 hours … upon information and belief, individuals have already been loaded onto buses.”

A spokeswoman for the Department of Homeland Security declined to respond to a request for comment on the ACLU’s claims. “We are not going to reveal the details of counter terrorism operations, but we are complying with the Supreme Court’s ruling,” Tricia McLaughlin said in an email statement.

At the Friday night court hearing in Washington, Chief U.S. District Judge James E. Boasberg described the notices the detainees had received as “very troubling.”

“I strongly doubt that the notice, particularly with a short time frame, complies with the Supreme Court instruction, where it doesn’t give anything about the right to challenge or seek a hearing,” Boasberg said. But the judge ultimately concluded he did not have jurisdiction to intervene and that the matter was up to the 5th Circuit and the Supreme Court.

In March, Boasberg temporarily blocked the administration from using the Alien Enemies Act for deportations as the first flights to El Salvador were in the air — a ruling the Supreme Court later overturned. But earlier this week, the judge launched a criminal contempt inquiry after finding probable cause that Trump administration officials willfully violated his order while it was in place. The federal appeals court for Washington Friday put on hold Boasberg’s decision pending its review.

Earlier this week, Judge James Wesley Hendrix of the U.S. District Court for the Northern District of Texas denied the ACLU’s initial request to block the removals of two men targeted for deportation. The judge concluded that the men did not face “imminent risk” of removal because the government said it had “no present plans to remove” them until the case was resolved and that it would tell the court if that changed.