(CNN) About 4,000 migrants apprehended by US Customs and Border Protection in Del Rio, Texas, over the last weeks have been expelled under a public health authority, known as Title 42, and 10,000 to 12,000 migrants have been released into the United States, Homeland Security Secretary Alejandro Mayorkas said Sunday.
"That is a public health authority. It is not an immigration policy. It is exercised as the CDC, the Centers for Disease Control (and Prevention), has ordered, in light of the arc of the pandemic," Mayorkas told CNN's Jake Tapper on "State of the Union." "The public has to remember that we are in the midst of a pandemic. The Delta variant caused a setback. ... This is a public health imperative to protect migrants themselves, local communities, our personnel and the American public."
He also said there are about 13,000 migrants who arrived in Del Rio in that same timeframe that have been put in immigration proceedings to determine whether they can remain in the US or be removed. Approximately 10,000 to 12,000 migrants who were detained in Del Rio, Texas in recent weeks have also been released into the United States, Mayorkas said during a separate interview with Fox News.
"It could be even higher," Mayorkas said Sunday. "The number that are returned could be even higher. What we do is we follow the law as Congress has passed it."
It's the latest update on the repatriation of migrants who amassed in Del Rio. The Department of Homeland Security has been conducting regular repatriation flights to Haiti.
On Saturday, it conducted five repatriation flights, including three flights from Del Rio, Texas to Port-au-Prince, Haiti and two flights from Del Rio, Texas to Cap Haitien, Haiti.
In March 2020, the Trump administration invoked the public health order, Title 42, that allowed border officials to turn back migrants encountered at the US-Mexico border, a move that in effect sealed off the border. Public health officials, at the time, suspected political motivations behind the decision. The Biden administration has relied on the public health order to turn away adults and families apprehended at the US southern border. Unaccompanied children remain exempt from the policy.
Pressed on Democrats' criticism of the removal of Haitian migrants and continued use of the policy, Mayorkas defended the Biden administration's immigration actions.
The makeshift migrant camp under a Texas bridge
Crews clear the makeshift migrant camp along the Del Rio International Bridge in Del Rio, Texas, on Friday, September 24.
Migrants prepare to board a bus toward Houston provided by a humanitarian organization after they were released from US Customs and Border Protection custody in Del Rio on Thursday, September 23.
The makeshift camp under the Del Rio International Bridge is seen with a large portion of the area cleaned up as authorities continue to process and remove migrants in Del Rio on September 23.
Migrants camp under the Del Rio International Bridge on Tuesday, September 21.
Vehicles line up along the banks of the Rio Grande near the Del Rio encampment on September 21. Texas Gov. Greg Abbott said officials are using "unprecedented" methods to deter migrants from crossing into the state, including parking Texas National Guard and Texas Department of Public Safety vehicles for miles along the border to create a
"steel barrier."
This aerial photo shows the Del Rio camp on September 21.
Migrants cross the Rio Grande between Del Rio and Ciudad Acuña, Mexico, on Monday, September 20. Migrants staying at the Del Rio International Bridge have been going to Ciudad Acuña to buy food and supplies.
US Border Patrol agents watch migrants cross the Rio Grande on September 20.
Migrants fall in the mud after wading across the Rio Grande back into Mexico on September 20.
A migrant carries his belongings above water as he crosses the Rio Grande back into Mexico.
Migrants wait to be processed near the Del Rio International Bridge on Sunday, September 19.
A US Border Patrol agent on horseback tries to stop migrants on the banks of the Rio Grande on September 19.
A father cradles his son on the Mexican side of the Rio Grande on September 19.
Migrants wade across the Rio Grande on September 19.
US Border Patrol agents confront migrants in Del Rio on September 19.
Migrants cross the Rio Grande to get food and supplies in Ciudad Acuña on Saturday, September 18.
In this photo provided by law enforcement, migrants take shelter under the Del Rio International Bridge that connects Del Rio with Ciudad Acuña.
Migrants use a dam to cross to and from the United States from Mexico on Friday, September 17.
Migrants are seen in the makeshift camp in Del Rio on September 17.
Migrants bathe in the Rio Grande near the Del Rio International Bridge on September 17.
Asylum seekers wait to turn themselves in to Border Patrol agents near the bridge in Del Rio on Thursday, September 16.
Migrants wade in the Rio Grande on September 16.
Migrants gather near the bridge as they wait to be processed in Del Rio on September 16.
Migrants wade in the Rio Grande on September 16.
Asylum seekers wait to turn themselves in under the Del Rio International Bridge.
Cuban asylum seekers Otto Jesus, center, and his longtime partner, Yanet, left, board a bus after being processed by authorities in Del Rio on September 16.
Makeshift shelters are seen near the Del Rio International Bridge on September 16.
Migrants cross the Rio Grande from Ciudad Acuña on September 16.
Clothes are laid out on the ground to dry under the International Bridge in Del Rio on Wednesday, September 15.
"This administration, the Biden-Harris administration, has indeed rescinded the immoral, unethical and cruel policies, and we are rebuilding a system that's been entirely dismantled by the prior administration," Mayorkas said on CNN, adding that the administration studied conditions in Haiti prior to removing Haitians.
The secretary also punted to the CDC when asked about the public health authority that allows the administration to swiftly remove migrant families and adults encountered at the border.
"If they determine that the public health imperative no longer exists and Title 42, which is a statute, a law, need not be applied to protect people, then it will not be applied any longer and we will proceed accordingly," Mayorkas said.
CNN's Geneva Sands contributed to this report.