NUEVO LAREDO, Mexico — When the United States began sending asylum seekers to wait in Mexico earlier this year as their claims were processed, many regarded the dangerous northeastern state of Tamaulipas as a worst-case scenario.

The State Department warns against all travel to Tamaulipas — the same risk level it has assigned Syria and Afghanistan. Doctors Without Borders reports that 45 percent of its recent patients in this city, among the largest in the state, were migrants who had “suffered at least one episode of violence” while waiting here to cross the U.S. border.

But on Tuesday morning, the United States sent the first 12 migrants back to Tamaulipas under a program known as the Migration Protection Protocols. Mexican authorities dismissed the group from Nuevo Laredo’s immigration office without any transportation or assistance.

“Where do we go?” said José Luis Romero, 31, who had fled Venezuela with his wife and two sons, ages 6 and 8. “We gave away our mattresses.”

The family had waited for three months in Nuevo Laredo before U.S. officials called for them Monday morning and took them across the border to Laredo, Tex. Romero was separated from his wife and children, and immigration officials interviewed the couple separately. The two explained how they had protested Venezuelan President Nicolás Maduro in the city of Maracaibo and how security forces had later raided their home.

On Tuesday — after their interviews, without warning — they were shipped back across the border with their children, their next court date scheduled for Sept. 24.

“No one told us they would send us back here to wait,” Romero said.

He and his family dragged their luggage through the streets for a few blocks. It was 97 degrees at 11 a.m. For months, he had tried to keep a low profile here after hearing of other migrants being kidnapped. Now he was left to find a new place to stay. The other returnees — all Cubans — had headed off in a different direction.

“I was told not to talk to anyone because of my accent, not to leave the shelter, because we are targets,” Romero said.

For months, the city’s shelters had been overflowing. Some migrants who left to work or buy food were seized by armed groups. Aaron Mendez Ruiz, who runs a shelter called Amar, said 15 migrants from the facility have been kidnapped this year. One was a Cuban man, Carlos Cordero Roque, 31, who was released Sunday night with bruises lining his back.

Recently, the armed men have been demanding payments of $5,000 from migrants, assuming their relatives in the United States will pay. Roque was held for two weeks before the money arrived, he said.

“There’s no question that they specifically go after the migrants,” Ruiz said.

Eventually, on Tuesday, Romero called the manager of a different migrant shelter who sent a white truck to pick up the family from a street corner.

The Trump administration developed the Migrant Protection Protocols program to reduce the number of migrants who live and work in the United States while they wait for their asylum hearings — in some cases for years as a result of the backlog in U.S. asylum courts.

By June, 11,000 migrants had been sent back to Mexico, mostly to Tijuana and Ciudad Juarez, to await hearings. But the U.S.-Mexico migration deal last month has allowed for the program’s rapid expansion.

Mexican officials said they expected tens of thousands of asylum seekers to be returned over the next several months. There was no way to accommodate them, they said, without launching the program in Tamaulipas, where migrants have been targeted for years.

In 2010, 72 migrants were killed in San Fernando, in rural Tamaulipas. Police found their decomposing bodies and later accused the criminal syndicate Los Zetas of the killings.

State officials voiced outrage at the new U.S. policy.

Tamaulipas “will not be a crossing point for returned asylum seekers,” the governor, Francisco Javier García Cabeza de Vaca, said in a statement on Monday.

“Our shelters are already overwhelmed,” Raúl Cárdenas, the city manager of Nuevo Laredo, said in an interview. “We don’t have the resources to handle this.”

Cabeza de Vaca and officials in Nuevo Laredo threatened to send the migrants to a different state, farther from the border. They complained that Mexico’s federal government had signed a deal with the Trump administration without consulting or assisting the border states involved.

“We think it would be better to create a shelter 30 or 50 miles south,” said Salvador Rosas, a congressman from Tamaulipas.

On Tuesday, Tamaulipas officials suggested that such a shelter could be built in the city of Colombia in the neighboring state of Nuevo León, 30 miles northwest of Laredo, Tex.

That plan would complicate the legal process for asylum seekers, who already struggle to find immigration attorneys willing to travel to Nuevo Laredo. The Department of Homeland Security gives returnees a list of lawyers in South Texas, but many say they are unwilling to meet with clients in Nuevo Laredo because of security concerns.

“I don’t know any pro bono immigration lawyers who are ready to tend to this group,” said Nelly Vielma, an immigration attorney and a Laredo City Council member. “Right now, we are trying to figure out if we can handle some of the cases over Skype.”

Julieta Vences, who leads the migration caucus in Mexico’s National Congress, said no migrants would be forced to leave Tamaulipas. But the state and city governments control how and where resources are distributed to migrants.

While President Andrés Manuel López Obrador has spoken about the need to respect migrants’ rights, his administration so far has done little to assist those waiting in northern Mexico.

This city’s largest migrant encampment is a telling example. It is a municipal homeless shelter, where asylum seekers are allowed to sleep in a parking lot — if they can afford their own tents. Food is not provided. Other shelters, such as Amar, are funded by religious charities.

López Obrador’s administration has said it is aware of poor conditions in migrant shelters and is working to improve them.

Authorities here appeared unprepared to handle the return of asylum seekers, telling Romero and the others they would have to try their best to find a place to stay.

Later on Tuesday, Romero was able to return to the small apartment in Nuevo Laredo he had rented for six weeks, for $100 a month, before he and his family were called across the border. Unlike many asylum seekers, he has relatives in the United States who can send him money.

The Mexican government issued him a work visa, he said, fulfilling a López Obrador pledge to allow migrants to earn money while awaiting their court dates in the United States. But Romero has no intention of using it.

“As dangerous as this city is, I’m not going outside unless I have to,” he said.