The Department of Homeland Security is laying the groundwork for a plan to transport recent border crossers by plane to cities around the U.S. and release them after processing, according to two DHS officials familiar with the plan.

Florida officials expressed anger on Thursday after learning that the Trump administration was planning to release hundreds of migrants in Broward and Palm Beach counties each month.

Beyond South Florida, DHS is considering other areas around the country where immigrants can be released, the two officials told NBC News. A Customs and Border Protection official, who held a conference call with reporters Friday afternoon, said the agency is primarily interested in communities along the northern border and on the coast, where there is already a border patrol presence.

A DHS official said previously the agency was looking at places with the capacity to process large numbers of immigrants, but declined to give further specifics on cities or regions under consideration.

Central American migrants who cross the U.S.-Mexico border must be processed before they can be released. Many make a claim for asylum, seeking the right to stay in the country to avoid persecution back home.

Customs and Border Protection would be responsible for identifying which migrants to put on planes bound for the interior of the country, and the agency would rely primarily on Immigration and Customs Enforcement airplanes. The CBP official said on Friday that ICE would contract the planes and not look for additional federal assistance.

There are no plans to detain migrants in the cities where they are released, the officials said. Officials in Broward County, Florida have expressed concern about migrants being released without “designated shelters or funding to house them, feed them, and keep them safe,” according to a statement released Thursday.

A similar program is in place in Del Rio, Texas where immigrants have been airlifted from the Rio Grande Valley. CBP has said that the hundreds of immigrants released there are non-criminal families.

The CBP official said the plan to fly immigrants to cities across the country is a contingency "if the flow [of immigrants] continues to increase."

In both March and April, more than 100,000 undocumented immigrants crossed the border over the span of a month, numbers not seen in over 12 years.

Following news reports last month, President Donald Trump said he would consider sending immigrants specifically to so-called "sanctuary cities" — often led by Democrats — where officials have limited cooperation between local law enforcement and ICE. The officials said the decisions being made now on where to transport migrants are not political and would not specifically target sanctuary cities.

Spokespeople for the Department of Homeland Security and Customs and Border Protection declined to comment on the plan to send immigrants to South Florida. They did not respond to a request for comment about a broader plan to fly immigrants to cities across the country.