Just two weeks after U.S. Border Patrol agents began housing asylum-seeking migrants in a new tent facility in Donna, the agency announced Friday it had reached capacity and the agency will construct four additional temporary facilities in two other Rio Grande Valley cities.

The facility in Donna was completed the first week of May and can hold 500 undocumented immigrants after they are apprehended or turn themselves into Border Patrol officials.

But in a new release Friday, the agency said agents in the Rio Grande Valley sector had 8,000 migrants in custody, a result of the continued “waves of migrants fleeing El Salvador, Guatemala and Honduras.” The additional structures are being built at Border Patrol stations in McAllen and Rio Grande City.

“The longer illegal aliens remain in custody, the harder it can become to sustain our operations but housing the migrants in these tents is the default solution,” Chief Patrol Agent Rodolfo Karisch said in a statement. “This is the reality of what happens when we simply cannot handle the influx of migrants arriving.”

The announcement comes after CNN published photographs of migrants, including children, sleeping on the concrete grounds of Border Patrol facilities. Photographs of the new facilities provided by U.S. Customs and Border Protection show military-style structures that can be built quickly and moved to locations as they are needed.

That’s different from the facility opened in Donna, which is a larger structure equipped with showers and separate dormitories. A similar structure opened in El Paso the same week.

A spokesperson with the U.S. Border Patrol said Friday that he couldn’t say how many people the new tents will hold but that they are similar to a tent set up in March in El Paso that can hold hundreds of people.

Since October 2018, when the federal government’s current fiscal year began, more than 460,000 undocumented immigrants have been apprehended on the southern border, already surpassing 2018's fiscal year total of 396,579. That total includes about 101,860 family units and 19,000 unaccompanied minors in the Rio Grande Valley, according to CBP statistics.