The flood of children crossing the Mexican border illegally and without their parents has slowed down in recent weeks, two senior Obama administration officials said Friday.

Border Patrol agents in the Rio Grande Valley in south Texas have found fewer than 500 children crossing the border illegally this week, the officials said. Last month, agents arrested as many as 2,000 child immigrants a week.

The Obama administration has been struggling to deal with a flood of more than 57,000 children traveling alone since Oct. 1. Homeland Security Secretary Jeh Johnson said earlier this month that as many as 90,000 unaccompanied child immigrants could be apprehended by the end of the budget year in September. Most of the children are from Honduras, El Salvador and Guatemala.

Guatemalan President Otto Perez Molina, Honduran President Juan Orlando Hernandez and El Salvadoran President Salvador Sanchez Ceren will meet with Obama and Vice President Joe Biden next week. Biden has been the point person for contacts with these Central American leaders. He last spoke to them by phone on July 9 and was in Guatemala for meetings on June 20.

The U.S. has been urging those governments to take steps to stem the exodus of children and warning that the U.S. will take steps to send them back promptly.

The volume of child immigrants has significantly taxed resources at the Homeland Security and Health and Human Services departments in recent months and prompted President Barack Obama to ask Congress to approve an emergency $3.7 billion spending bill to deal with the situation he has called an “urgent humanitarian crisis.”

The officials, who spoke on the condition of anonymity because they were not authorized to publicly discuss the latest trends in border arrests, said Friday it’s too soon to know what has led to drop in border arrests. They said illegal border crossings along the Mexican border tend to slow during the summer.

Along with dealing with the flood of children traveling alone, the Border Patrol has also arrested more than 55,000 people traveling as families, mostly mothers with young children.

Because of a lack of detention space, many of those people have been released with a notice to report back to immigration authorities at a later date.

In recent weeks, the Homeland Security Department has opened a family detention center with space for as many as 700 people center in Artesia, N.M., at the Border Patrol’s training facility. Immigration and Customs Enforcement announced Friday that a detention center in Karnes County, Texas, would be converted to house families starting in the next few weeks. That facility currently has space for 600 people.