The number of illegal immigrants apprehended at the U.S.-Mexico border continued to climb during the month of May, according to recently released Customs and Border Protection data.

Last month CBP detained 40,366 illegal immigrants attempting to cross into the U.S. unlawfully, the most in a single month since July 2014. This fiscal year to date, CBP has apprehended 264,192 illegal immigrants at the U.S.-Mexico border.

Included in May’s apprehension numbers were 6,788 illegal immigrants traveling as “families” and 5,669 unaccompanied “minors.” Notably, the 44,524 total family members apprehended in the first eight months of this fiscal year exceed the 39,838 apprehended for the entirety of FY 2015. The 38,566 unaccompanied minors apprehended at the border this fiscal year to date is nearly as high as the total reached for the year in FY 2015.

The high apprehension levels have had officials anxious about a possible repeat of the FY 2014 humanitarian crisis at the border, when record levels of Central American minors and families flooded into the U.S., straining resources and capacity. While this year’s totals have been high, they have not yet exceeded the numbers reached in FY 2014 when a total of 68,541 unaccompanied minors and 68,445 family members were apprehended at the border.

The majority of the unaccompanied minors and family units apprehended are from El Salvador, Honduras and Guatemala. The Obama administration has repeatedly blamed “push factors,” like violence, for the migration northward. Immigration hawks and Republicans, however, have pointed to a dramatic decline in immigration enforcement, executive amnesty, and policies like catch-and-release as enticements for illegal migration.

Brandon Judd, the president of the National Border Patrol Council, for example, has estimated that at least 80 percent of the illegal immigrants CBP apprehends at the border are released into the U.S.

“In essence we are just letting them come into the United States,” Judd testified at a Senate hearing last month.

In response to the ongoing surge in illegal immigration at the border the Obama administration has opened up an alternate channel for Central American minors with parents living in the U.S. to come to the country.

“To date, the Central American Minors Program has received applications for 8,948 individuals, and we have approved more than 1,448 individuals for refugee status or parole in El Salvador, Honduras, and Guatemala,” CBP said in a statement. “We also continue to work with our federal partners, particularly the Department of State, to address underlying conditions that currently exist in Central America.”