EL PASO, Texas (AP) Pandemic-related asylum restrictions that expelled migrants millions of times were lifted early Friday in a shift that threatened to put a historic strain on the nations beleaguered immigration system, as migrants raced to enter the United States before new restrictions set in.

Meanwhile, the administration was dealt a potentially serious legal setback when a federal judge temporarily blocked its attempt to release migrants more quickly when Border Patrol holding stations are full.

Migrants, including children, in northern Mexico paced along a U.S. border strung with razor wire and bolstered by troops, unsure of where to go or what to do next. Others settled into shelters determined to secure an asylum appointment that can take months to schedule online.

The expiring rules, known as Title 42, have been in place since March 2020. They allow border officials to quickly return asylum seekers back over the border on grounds of preventing the spread of COVID-19.

U.S. authorities have unveiling strict new measures, which crack down on illegal crossings while also setting up legal pathways for migrants who apply online, seek a sponsor and undergo background checks. If successful, the reforms could fundamentally alter how migrants arrive at the U.S.-Mexico border.

Many migrants were acutely aware of looming policy changes designed to stop illegal crossings and encourage asylum seekers to apply online and consider alternative destinations, including Canada or Spain.

I dont know whats going to happen, said Jhoan Daniel Barrios, a former military police officer from Venezuela as he paced with two friends along the the border in Ciudad Jurez, across from El Paso, Texas, looking for a chance to seek refuge in the U.S.

We dont have any money left, we dont have food, we dont have a place to stay, the cartel is pursuing us, said Barrios, whose wife was in U.S. custody. What are we going to do, wait until they kill us?

Last week, Barrios and his friends entered the U.S. and were expelled. They had little hope of a different result Thursday.

On the U.S. side of the river, many surrendered immediately to authorities and hoped to be released while pursuing their cases in backlogged immigration courts, which takes years.

It was not clear how many migrants were on the move or how long the surge might last. By Thursday evening, the flow seemed to be slowing in some locations, but it was not clear why, or whether crossings would increase again after the coronavirus-related restrictions expire.

A U.S. official reported the Border Patrol stopped some 10,000 migrants on Tuesday nearly twice the level from March and only slightly below the 11,000 figure that authorities have said is the upper limit of what they expect after Title 42 ends.