(NewsNation) — Shelters across the southern border are overwhelmed by large numbers of migrants, many of whom crossed into the U.S. before the expiration of Title 42.

In areas like San Diego County in California, agents are reporting a significant drop in daily encounters.

Migrant apprehensions are reaching an average of 4,000 a day, compared to the historic average of 10,000 apprehensions a day in the days leading up to the end of Title 42, officials report.

Despite this drop, hundreds of migrants who were already in the U.S. are now being processed and taken to shelters such as those run by Catholic Charities in the San Diego area.

These shelters work with the federal government to help migrants coordinate travel after they buy plane or bus tickets to reach family members or sponsors around the U.S.

But some are worried about migrants staying in their communities permanently.

El Cajon Mayor Bill Wells wrote a letter to the White House demanding more resources to assist with migrants, saying residents are concerned.

“People are very concerned about their safety, they’re concerned about the homeless problem increasing, which would be a terrible thing, and they’re really concerned about the uncertainty. They don’t know who’s coming. We have no idea how many of these people have criminal records,” Wells told NewsNation.

El Cajon is already facing a homelessness problem and is one of three locations in the county set for migrant releases if Border Patrol processing centers get overcrowded, something the community has experienced before.

San Diego County Supervisor Jim Desmond said he feels abandoned by the federal government in dealing with the migrant surge — and that he felt more concerned when an Afghan national on the FBI terror watchlist crossed into the San Diego region.

“It begs the question of how many others have made the attempt and didn’t get caught coming across our borders. Same thing with fentanyl. Fentanyl has been pouring across our borders here recently,” Desmond said.