Updated September 24, 2021 at 4:01 PM ET

There are no longer any Haitian migrants in the camp under the Del Rio International Bridge in Texas, Homeland Security Secretary Alejandro Mayorkas told reporters Friday.

The camp grew to hold 15,000 people at one point, with a total of nearly 30,000 migrants passing through since Sept. 9, Mayorkas said. He called it an "unprecedented" number.

The U.S. has been putting Haitians on expulsion flights since Sunday, as the Biden administration enforces a Trump-era public health order expelling migrants without giving them a chance to seek asylum.

Under that order, known as Title 42, DHS has flown about 2,000 migrants on 17 flights to Haiti, Mayorkas said. Around 8,000 people decided to return to Mexico voluntarily, he said.

The massive migrant camp has put a spotlight on the Biden administration's border policies, particularly after U.S. Border Patrol agents were photographed using their horses — and, in at least one instance, long reins — to chase Haitian migrants.

President Biden said Friday that the agents' actions were "outrageous" and promised consequences for those responsible for the controversial incident at the border.

Title 42 is not an immigration policy, Mayorkas says

The Biden administration has faced intense criticism over the Title 42 expulsions, including charges that they are inhumane and immoral. Mayorkas emphasized Title 42's status as a public health order, stating, "It is not an immigration policy."

About 12,400 migrants who were at the camp will have their cases heard by immigration judges to determine whether they can remain in the United States. Some of them are being housed in Customs and Border Protection centers, while others have been released pending their court hearings, the secretary said.

More than 5,000 people are still being processed by DHS to determine whether they should be expelled immediately or whether their cases should be handled by immigration judges.

Mayorkas reiterated that his agency is pursuing a quick conclusion of its investigation into the CBP's horse patrol units — and he said he would make the report public.

Biden condemns border agents' actions as 'horrible'

Biden was asked about the agents' actions near the international bridge in Del Rio during a news briefing Friday morning. Photos from the border interdiction quickly triggered outrage in the U.S. and beyond as well as criticism of the Biden administration's policy of rounding up Haitian migrants to be deported.

Asked whether he takes responsibility for the chaos that has emerged at the border, Biden replied, "Of course I take responsibility. I'm president," adding it was "horrible" to see how federal agents treated the migrants.

"To see people treated like they did — horses [unintelligible] running them over, people being strapped. It's outrageous. I promise you, those people will pay," Biden said.

The president noted that the matter is being investigated.

"It's an embarrassment — it's beyond an embarrassment," Biden added. "It's dangerous, it's wrong. It sends the wrong message around the world; it sends the wrong message at home. It's simply not who we are."

Horse patrols at that part of the border are now suspended, White House press secretary Jen Psaki said on Thursday. Earlier this week, Psaki repeatedly called the scene "horrific."

Many of the migrants who were caught up in the border agents' actions were attempting to bring food back from Mexico to the huge encampment under the international bridge in Del Rio.

Most of the migrants are from Haiti, although some are from Cuba, Brazil and other countries.

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