Nearly 10,000 immigrant families and unaccompanied children were arrested while crossing the US-Mexico border in August, the Border Patrol says.
The agency published statistics Monday that showed an increase in the number of border crossings.
Over 35,000 children traveling on their own and more than 34,500 families, mostly mothers and children have been arrested since the start of the fiscal year in October.
White House spokesman Josh Earnest reacted to the matter, but failed to provide a reason for the "surprising uptick" which has caused a "concern" for the administration of US President Barack Obama.
Earnest said the administration continues to warn people not cross the borders illegally.
Many of the migrants are fleeing violence in Honduras, El Salvador or Guatemala, according to the Associated Press.
GOP’s 2016 presidential candidates have already focused part of their campaign on attempts to curb the inflow of migrants, with Donald Trump even suggesting a all should be built on the border.
Trump's plan leaves no option except for mass deportation of the estimated 11 million people in the US illegally. "They have to go," he has said.
Observers believe rising violence in Central America has accelerated the immigration pace in recent years. Honduras has the most murders per capital of any country.