'Surprising' Uptick in Unaccompanied Children Crossing Border in August, White House Says The Customs and Border Protection Service was set to release new numbers.

 -- There has been a spike in the number of people illegally crossing the southwestern U.S. border in August, including a significant uptick in unaccompanied children, ABC News has learned.

Big Bend and Yuma are two regions experiencing significant increases. The number of families illegally crossing the border into Big Bend surged 251% compared to last year; for unaccompanied children the rate increased 169%.

Yuma reported a 130% spike in families and a 177% jump in unaccompanied children.

The new numbers show significant increases in regions where human traffic was lowest in 2014, including the El Paso region, Big Bend, San Diego, and Yuma.

"In August, U.S. Customs and Border Protection experienced an increase from the month of July in the number of unaccompanied children and family units apprehended," a Customs and Border Protections spokesperson told ABC News. "Overall, the number of Unaccompanied Alien Children (UAC) apprehensions in 2015 remains significantly lower compared to the number of apprehensions through August of last year, with a 46 percent decrease."

The federal government has added more resources at the border to handle the growing number of unaccompanied children crossing illegally.

It even launched a “Dangers Awareness” campaign in Central American countries, which served to drive the numbers down until last month. The majority of children crossing have been coming from Guatemala, Honduras and El Salvador.

“We have seen...in the month of August, a surprising uptick, and it still is below -- far below the levels that we saw at the peak last year," White House Press Secretary Josh Earnest said. "In August, the numbers decline because of the weather patterns. Instead, we saw an increase. So that is something that is concerning.”

More than 5,000 family units were apprehended in August alone, nearly the same number of unaccompanied minors.

"Since July, we have seen the number of referrals of unaccompanied children to HHS continue to increase to a total of nearly 4,400 in August," an HHS spokesperson tells ABC News. "In FY 2015, so far, approximately 31,000 unaccompanied children have been referred to the HHS Office of Refugee Resettlement. Out of an abundance of caution and to ensure we have sufficient bed capacity this fall, we have decided to increase the capacity of our current providers to between 8,500 and 8,700 beds at the beginning of Fiscal Year 2016."

Total apprehensions of unaccompanied children and family units are around half what they were at the same time last year.

ABC's John Parkinson contributed to this report.