Hundreds of US troops to arrive at the border today as migrants' anxieties rise ahead of Title 42's expiration

Hundreds of US troops are set to begin a new mission along the southern border Wednesday as officials and a surge of migrants brace for what's to come when a Trump-era border restriction policy expires late Thursday.

Laredo Mayor Victor Trevino told "CNN News Central" with Jim Sciutto Wednesday that his southern Texas border city is preparing for the end of the pandemic-related restrictions as "if it's a hurricane coming."

Trevino said Laredo is expecting migrants to be transferred from overburdened processing centers in Brownsville and El Paso. He said the "great scale" of the crisis required federal reform that includes better immigration processes.

Some 550 troops, mostly from the Army, will support US Customs and Border Protection by monitoring the border and doing data entry and warehouse support, US Northern Command spokesperson John Cornelio said.

"They will not be conducting any type of law enforcement activities" and won't interact with migrants, Pentagon spokesperson Brig. Gen. Pat Ryder said Tuesday of the troops.

Another 950 troops, largely from the Marines and Army, will arrive by the end of the month, Cornelio said.

Immigration officials are already dealing with a surge of migrants, even before the expiration of Title 42, a 2020 policy that allowed US authorities to swiftly expel migrants encountered at the southern border, with some exceptions, ostensibly to curb the spread of Covid-19.

Federal authorities have warned that the policy's expiration Thursday at 11:59 p.m. ET could further increase the number of migrants trying to cross into the US and intensify an already challenging humanitarian crisis at the southern border.

The latest border crisis has sent ripples across the country: Troops are being deployed to border cities overwhelmed with desperate migrants anticipating the end of Title 42; states and municipalities far away from the southern frontier brace for an influx of newcomers; and political tensions mount over a long broken immigration system facing one of its greatest challenges yet.

Department of Homeland Security Secretary Alejandro Mayorkas on Wednesday touted the "effectiveness" of the administration's efforts to stem the flow of migration at the border and criticized Congress for failing to repair "a broken immigration system." He also emphasized that the end of Title 42 "does not mean our border is open."

"Even after nearly two years of preparation, we expect to see large numbers of encounters at our southern border in the days and weeks after May 11," he said.

"This places an incredible strain on our personnel, our facilities and our communities, with whom we partner closely. Our plan will deliver results, but it will take time for those results to be fully realized, and it is essential that we all take this into account."

The expiration of Title 42 does not signal an open border but rather "means tougher consequences (under Title 8) for people who crossed the border illegally," said the secretary, citing a five-year bar on reentry for migrants entering the country unlawfully.

Mayorkas said the department is "surging personnel to the border," including 1,400 DHS personnel, 1,000 processing coordinators and an additional 1,500 Department of Defense personnel.

Agents with US Secret Service and US Marshals Service, among other federal agencies, are expected to deploy to help border authorities, two Homeland Security officials told CNN.

Crowds of migrants released on humanitarian parole gathered outside the offices of the non-profit Team Brownsville in Texas - which is adjacent to a bus station - on Wednesday. They included migrants from China, Venezuela, and Central American countries who clutched blue bags with belongings and manila envelopes with immigration documents.

Team Brownsville processed 844 migrants on Tuesday, including 30 children, and is operating at capacity, according to volunteer coordinator Andrea Rudnik. The non-profit has been receiving 800 to 1,000 asylum seekers a day over the last two weeks, she said.

"We need to find space and be prepared to have enough water, food, and other kinds of things that people need when they get here," she said.

A Venezuelan migrant told CNN Wednesday that he arrived with his family in Brownsville nearly one week ago and lost track of them while being processed by immigration authorities.

The migrant, who asked that only his first name be used - William - said he was separated from his wife and two children and has not been able to locate them.

"I am asking them where she is, and they say they don't know," William said of his wife.

William said the end of the pandemic-era immigration restrictions is the reason "why I came now" to the US border.

Migrant arrivals along the whole southern border already are on an upswing. Authorities encountered about 10,400 migrants Tuesday, according to a Homeland Security official, up slightly from the nearly 10,000 migrants encountered Monday and continuing an upward trend.

More than 28,000 migrants were in Customs and Border Protection custody as of Wednesday morning, the official said. And about 155,000 migrants are estimated to be in shelters and on streets across northern Mexican states bordering the US, according to a source familiar with federal estimates.

Federal agents reacting to a steep increase of migrants in El Paso over the past week leaned on migrants there Tuesday to turn themselves in to immigration authorities.

Agents handed out flyers to those who'd been living on sidewalks outside a church to ask them to visit a Customs and Border Protection enforcement center for processing. The flyers informed recipients they'd be "processed by CBP officers and placed on the correct immigration path."

Hundreds turned themselves in Tuesday for immigration processing in El Paso, a source familiar with the data told CNN. By Tuesday night, only about 150 migrants remained outside the church - down from about 2,000 at one point earlier in the week, El Paso County Commissioner Dave Stout said.

Some migrants outside the church were too scared to surrender to authorities and confused about what would happen next, they told CNN.

"We've heard we're going to be deported - that our papers are no good," said Nelson Pirela, a migrant from Venezuela. "We heard immigration is coming and that we have to turn ourselves in."

"People are nervous, they're scared," he said.

Many heading to the US are making long and dangerous treks in hopes of finding a better, safer life for their families. People immigrate to flee violence, for economic opportunities or to reunite with family members, experts say.

"Like many others, we are looking for a better way of life. We're looking for safety to go out in the streets," migrant Marcela Aguilar told CNN affiliate KGTV in San Diego.

As the Title 42 expiration looms, US officials said they're prepared for what's to come.

Officials are working closely with humanitarian nongovernmental organizations that support migrants and expanded transportation contracts, a senior Biden administration official said.

"We have been moving some individuals laterally along the border to other parts of the border where there is more capacity," the official said.

Still, President Joe Biden on Tuesday acknowledged the policy's expiration and the migrant surge expected to follow are "going to be chaotic for a while."

The administration is working to set up regional processing centers in countries migrants traverse on their way to the US southern border so they can apply there to come to the US, the president said. It's unclear when those centers will be running.

States and cities have also been preparing for the expected surge: Officials in Brownsville, Texas, are talking with bus operators and airlines about increasing outbound services and with nongovernmental organizations about expanding space for migrants.

"Several safety measures are also being enhanced to ensure the safety of the public and migrants," said Fire Chief Jarrett Sheldon, who runs emergency management for the city.

Title 42's imminent expiration is triggering official action far from the border, too. In New York, Gov. Kathy Hochul issued an executive order Tuesday allowing cities and the state to tap into more resources ahead of Title 42's expiration. And Chicago Mayor Lori Lightfoot issued an emergency declaration, saying the city's resources are now stretched to "the breaking point" and existing facilities are full.

As New York grapples with a surge in migrant arrivals, Orangetown, in Rockland County, was granted a temporary restraining order Tuesday to keep a hotel in the town from accepting 30 migrant men that the New York City mayor's office planned to send Wednesday, Town Supervisor Teresa Kenny announced.

Rockland County officials in recent days have criticized New York Mayor Eric Adams for not informing them about the city's plans to bus migrants to that county. Sending willing migrants to hotels outside New York City is part of what Adams called a "decompression strategy" as city shelter space runs out and migrant arrivals increase.

In El Paso, several migrants waited in line Tuesday under the blazing sun at a Customs and Border Protection Center with plans to turn themselves in. They'd crossed into El Paso undetected and wanted to surrender to immigration authorities in hopes of seeking asylum and pleading their case, they told CNN.

Among them were Katia Arzuza, her husband and their teenage daughter.

"We want the permit, but most importantly, the work permit, to be legal in the country," Arzuza told CNN. "We would like them to give us everything, permanent residency to stay in the country. We don't want to go back."

As Arzuza spoke, a border patrol officer told the trio that families with minors would go to the front of the line. The family hustled forward, uncertain what they'd find.

When Title 42 lifts, US officials will lean more on the decades-old Title 8, under which migrants could face more severe consequences for crossing the border unlawfully, such as being barred from entering the US for at least five years, they've said.

Asylum-seekers who cross the border without first applying for asylum could be removed under Title 8 authority.

While Title 8 carries more legal consequences, especially for those caught a second time, processing times under that authority take longer than Title 42 expulsions and could strain already pinched resources, creating a bottleneck amid heavy mass migration.

Border officials had already been apprehending migrants at the border under Title 8, with more than 1.15 million people apprehended under that authority at the southern border in fiscal year 2022, according to US Customs and Border Protection.

As the expiration of Title 42 approaches, some migrants in El Paso are growing desperate and at times falling victim to scams that promise legal paperwork and a chance to travel freely.

Erick Mendoza Caceres, a migrant from Honduras, on Tuesday held one of the flyers border officers were distributing, along with a document he said cost him $50 and guaranteed the ability to travel within the country.

"I want to be here legally, and I want to know if this paperwork is legal," Caceres said.

Caceres likely was a victim of one of the many scams being perpetrated against unknowing migrants desperate for documentation and answers, El Paso city officials told CNN.

"The concern is that there are some migrants that are being taken advantage of, purchasing fake documentation, and that is a concern for us because we cannot provide support if they're getting fake documentation," El Paso spokesperson Laura Cruz-Acosta said. "We need to provide true documentation, and that true documentation really comes from the federal government."

Despite the threat of being detained, Caceres was hopeful he could get clarity on the veracity of his paperwork, he told CNN.

Asked what he would do if he were deported, he broke down in tears.

CNN's Rosa Flores, Gloria Pazmino and Norma Galeana reported from El Paso, Texas, while Nouran Salahieh and Ray Sanchez reported and wrote in Los Angeles and New York. CNN's Priscilla Alvarez, Zachery Cohen, Steve Contorno, Oren Liebermann, Haley Britzky, Nick Valencia, Jason Morris and DJ Judd contributed to this report.