Conditions at informal migrant camps on the northern border are worsening, becoming increasingly unsanitary and crowded as more north-bound migrants arrive, according to a report by the Associated Press.

U.S. President Joe Biden has ended former president Trump’s “Remain in Mexico” policy, which forced asylum seekers to wait for their immigration court appointments in Mexico. President Biden also eased, but did not end, pandemic restrictions that prevent migrants from seeking asylum in the United States. But many migrants still have not been able to enter the U.S., and more keep arriving at the border.

One such camp is El Chaparral near the Tijuana-San Diego border crossing. Hundreds of families live under plastic tarps without bathrooms, and vulnerable to the weather and criminal gangs.

“The children are getting sick with diarrhea, they’re getting fevers and infections because there are a lot of flies around,” said Karitina Hernández, 63. “There is no sanitation, there is garbage around, excrement, urine.”

Hernández fled violence in Guerrero after a gang killed one of her sons and threatened her. She and her family have been living for weeks in a tent in El Chaparral. Her neighbors include roughly 2,000 migrants from Mexico, Haiti and Central America.

The Mexican Human Rights Commission issued a warning weeks ago about conditions in the camps and municipal authorities want to shut it down. But migrants fear that if they leave, they could miss their chance to enter the U.S.

A similar camp of asylum seekers in Matamoros, near Brownsville, Texas, was shut down in March. But more migrants keep arriving. Shelters in Tijuana ran out of room and migrants had nowhere to go.

The migrants are vulnerable to kidnapping and extortion by gangs, said Nicole Ramos, an activist with the migrant aid group Al Otro Lado.

“The United States says its laws and programs are there to protect the migrant community from traffickers, but now they are doing even more business,” Ramos said.

Another migrant, Armando Hernández, fled violence in Michoacán with his two sons. He expressed frustration with the admissions process.

“What proof do I need? To come here with my guts shot out?” he asked.

With reports from AP