U.S. Border Patrol agents are being reassigned from Maine to the Mexican border in response to large numbers of migrants crossing into the United States.

U.S. Customs and Border Protection operates six stations overseeing more than 20 land crossings along Maine’s 611-mile border with Canada. Known as the Border Patrol’s Houlton Sector, Maine’s stations are in Calais, Houlton, Fort Fairfield, Van Buren, Rangeley and Jackman.

Mike Niezgoda, spokesman for the Border Patrol’s Northeast operations, confirmed Saturday that an unspecified number of agents have been reassigned from Maine to ramped-up border operations in Southwest states.

“Due to fluctuations along the Southwest border, Houlton Sector has deployed additional border patrol agents to the Southwest border area of operations,” Niezgoda said in a written statement. “CBP seeks to deter and disrupt human smuggling activities by transnational criminal organizations and ensure our personnel are properly equipped to maintain border security.”

Niezgoda declined to say how many agents were being reassigned from posts in Maine because of “law enforcement sensitivities.” However, he said, more than 300 agents overall are currently being redeployed for this purpose, primarily from stations along the Canadian border and East and West coasts.

Maine shares borders with the Canadian provinces of Quebec and New Brunswick.

The number of migrants crossing into the United States from Mexico has skyrocketed to the highest levels in at least 15 years, and record numbers of teenagers and children arriving without parents have overwhelmed the government’s ability to care for them, according to The Washington Post.

U.S. agents took more than 171,000 migrants into custody last month, according U.S. Border Patrol figures that contradict President Biden’s claims that his administration is facing an influx no different from previous years.

Last month, CBP took in more than 18,800 unaccompanied minors, a 99 percent increase from February and a figure far above the previous one-month high of 11,861 in May 2019. The jump in the number of migrants arriving as part of family groups was even steeper last month, soaring to more than 53,000, up from 19,246 in February and 7,294 in January, the preliminary figures show.

The March data also shows the scope of the challenge faced by Border Patrol agents in the field who are trying to capture single adults crossing at levels not seen in years. Last month CBP detained more than 99,000 single adults, up from 71,598 in February.

CBP officials also say that they are struggling to intercept more-determined male entrants and that the number of “got aways” who are detected but not detained has risen to nearly 1,000 per day, the highest in recent memory.

The rapid increase in border arrests and detentions – which has more than doubled since January – underscores the magnitude of the challenge facing an administration that has promised more-humane and more-welcoming immigration policies.

Biden officials are racing to add thousands of emergency shelter beds to alleviate dangerous crowding in tent enclosures, where Central American teens and children are being held for longer than legal limits and sleeping shoulder to shoulder under foil blankets for days on end.

CBP announced Friday the opening of a new 90,000-square-foot tent facility near Eagle Pass, Texas, to help the agency cope with the volume of families and children in its care. A similar influx site is also under consideration in Arizona.

The U.S. Department of Health and Human Services has opened or is preparing to open nine emergency facilities, sending the minors to convention centers, converted oil-worker camps and military bases while it screens family members and eligible sponsors in the United States who can assume custody.