A federal judge has ordered an emergency halt to a plan by the Trump administration to send more than 600 unaccompanied Guatemalan children back to their home country — some within a matter of hours — after immigrant advocacy groups sued, calling the unannounced plan illegal.

U.S. District Judge Sparkle Sooknanan issued the order just after 4 a.m. Sunday, finding that the “exigent circumstances” described in the lawsuit warranted immediate action “to maintain the status quo until a hearing can be set.”

The judge, a Biden appointee, initially scheduled a virtual hearing on the matter for 3 p.m. Sunday, but later moved up the hearing to 12:30 p.m. after being notified that some minors covered by the suit were “in the process of being removed from the United States.”