The head of U.S. Customs and Border Protection said Tuesday he is stepping down as his agency is under siege over the discovery of dozens of children in filthy conditions at one of its stations in Texas.

Acting Customs and Border Protection Commissioner John Sanders said in a message to employees that he would resign on July 5. He did not give a reason for leaving his job.

'Although I will leave it to you to determine whether I was successful, I can unequivocally say that helping support the amazing men and women of CBP has been the most fulfilling and satisfying opportunity of my career,' he said.

Previously CBP's chief operating officer, Sanders was named acting commissioner in April after the agency's previous leader, Kevin McAleenan, became acting secretary of the Department of Homeland Security.

At the White House his ultimate boss, Donald Trump, denied that he had forced Sanders out, but said he 'knew' a change was coming at the top of the agency.

'I didn't speak to him, I don't think I've ever spoken to him,' he said.

Out: The acting commissioner of the U.S. Customs and Border Protection agency, John Sanders, is resigning and will leave his post on July 5

Outcry: Conditions at the Clint Border Patrol station have led to outrage. Lawyers who visited found inadequate food, lack of medical care, and older children trying to care for toddlers

TRUMP'S HIGH-PROFILE DEPARTURE LOUNGE Here are just some of the top officials who have left Trump's administration and when their departures were announced 2017 Inauguration Day was January 20 January 31: Acting Attorney General Sally Yates February 13: National Security Adviser Michael Flynn March 30: Deputy Chief of Staff Katie Walsh April 9: Deputy National Security Adviser K.T. McFarland May 9: FBI Director James Comey May 30: Communications Director Michael Dubke July 21: Press Secretary Sean Spicer July 28: Chief of Staff Reince Priebus July 31: Communications Director Anthony Scaramucci August 18: Chief Strategist Steve Bannon August 25: National security aide Sebastian Gorka September 1: Director of Oval Office Operations Keith Schiller September 29: Health and Human Services Secretary Tom Price December 8: Deputy National Security adviser Dina Powell December 13: Communications director for the White House Office of Public Liaison Omarosa Manigault Newman 2018 February 7: Staff Secretary Rob Porter February 28: Communications Director Hope Hicks March 6: Director of the National Economic Council Gary Cohn March 12: Special assistant and personal aide to the president John McEntee March 13: Secretary of State Rex Tillerson March 22: National Security Adviser H.R. McMaster March 28: Veterans Affairs Secretary David Shulkin April 10: Homeland Security Adviser Tom Bossert April 11: Deputy National Security Adviser Nadia Schadlow April 12: Deputy National Security adviser Ricky Waddell May 2: White House attorney Ty Cobb June 5: Communications aide Kelly Sadler July 5: Environmental Protection Agency Administrator Scott Pruitt August 29: White House Counsel Don McGahn October 9: U.N. Ambassador Nikki Haley November 7: Attorney General Jeff Sessions December 9: Chief of Staff John Kelly December 15: Interior Secretary Ryan Zinke December 20: Defense Secretary Jim Mattis 2019 March 8: Communications Director Bill Shine April 8: Homeland Security Secretary Kirstjen Nielsen June 13: White House Press Secretary Sarah Sanders June 18: Acting Defense Secretary Patrick Shanahan June 25: Acting Customs and Border Patrol Commissioner John Sanders July 12: Labor Secretary Alex Acosta July 28: Director of National Intelligence Dan Coats August 6: Ambassador to Russia, Jon Huntsman August 8: Deputy Director of National Intelligence, Sue Gordon August 29: President's personal assistant, Madeleine Westerhout September 5: Lead Middle East peace negotiator, Jason Greenblatt September 10: National Security Advisor, John Bolton October 11: Acting Homeland Security Secretary Kevin McAleenan October 17: Energy Secretary Rick Perry Advertisement

CBP is the agency that apprehends and first detains migrant parents and children crossing the U.S.-Mexico border.

Lawyers who visited facilities last week described squalid conditions to The Associated Press, which first reported on the complaints.

The conditions at the station in Clint, Texas, included inadequate food, lack of medical care, and older children trying to care for toddlers.

In one case, attorneys said a two-year-old boy without a diaper was being watched by older kids. Several had the flu.

Many were separated from extended family members like aunts and uncles who brought them to the border; others were teenage moms with babies.

Many children were moved out of the facility in recent days.

But around the same time that Sanders announced his resignation, his agency said officials have moved more than 100 kids back to the station.

An official from U.S. Customs and Border Protection said Tuesday that the 'majority' of the roughly 300 children detained at Clint, Texas, last week have been placed in facilities operated by the Office of Refugee Resettlement.

The official, who briefed reporters on the condition of anonymity, wouldn't say exactly how many children are currently detained there.

But the official says Clint is better equipped than some of the Border Patrol's tents to hold children.

Clara Long, a senior researcher with Human Rights Watch, and other lawyers inspected the facilities because they are involved in the Flores settlement, a Clinton-era legal agreement that governs detention conditions for migrant children and families.

The government has removed most children from the remote Border Patrol station.

Only about 30 children remained at the station outside El Paso on Monday, Rep. Veronica Escobar said after her office was briefed on the situation by a U.S. Customs and Border Protection official.

Most of the infants, toddlers and teens who were held at the Border Patrol station in Clint, Texas, were scheduled to be transferred by Tuesday to shelters and other facilities run by a separate federal agency, the Office of Refugee Resettlement said.

Attorneys involved in monitoring care for migrant children who visited Clint last week said older children were trying to take care of toddlers, The Associated Press reported Thursday.

They described a 4-year-old with matted hair who had gone without a shower for days, and hungry, inconsolable children struggling to soothe one another. Some had been locked for three weeks inside the facility, where 15 children were sick with the flu and another 10 were in medical quarantine.

'How is it possible that you both were unaware of the inhumane conditions for children, especially tender-age children at the Clint Station?' Escobar, a Democrat, said in a letter sent Friday to U.S. Customs and Border Protection acting commissioner John Sanders and U.S. Border Patrol chief Carla Provost.

Escobar asked to be informed by the end of this week what steps the officials are taking to end what she called 'these humanitarian abuses.'

Lawmakers from both parties decried the situation last week.

Border Patrol officials have not responded to AP's questions about the conditions at the Clint facility, but emailed a statement Monday that said: 'Our short-term holding facilities were not designed to hold vulnerable populations and we urgently need additional humanitarian funding to manage this crisis.'

Although it's unclear where all the children held at Clint were moved, Escobar said some were sent to another facility on the north side of El Paso called Border Patrol Station 1. Escobar said it's a temporary site with roll-out mattresses, showers, medical facilities and air conditioning.

But Long, an attorney who interviewed children at Border Patrol Station 1 last week, said conditions were not necessarily better there.

On the move: Migrants were photographed leaving the remote Border Patrol station in Clint after revelations about its squalid conditions

Protests: Immigration activists expressed outrage at the conditions children were kept in during a demonstration in the Russell Senate office building in the Capitol

'One boy I spoke with said his family didn't get mattresses or blankets for the first two nights, and he and his mom came down with a fever,' said Long, a senior researcher with Human Rights Watch. 'He said there were no toothbrushes, and it was very, very cold.'

Vice President Mike Pence, asked about the unsafe, unsanitary conditions for the children on 'Face the Nation' on Sunday, said 'it's totally unacceptable' and added that he hopes Congress will allocate more resources to border security.

Long and a group of lawyers inspected the facilities because they are involved in the Flores settlement, a Clinton-era legal agreement that governs detention conditions for migrant children and families. The lawyers negotiated access to the Clint facility with officials and say Border Patrol knew the dates of their visit three weeks in advance.

Many children interviewed had arrived alone at the U.S.-Mexico border, but some had been separated from their parents or other adult caregivers including aunts and uncles, the attorneys said.

Government facilities are overcrowded and five immigrant children have died since late last year after being detained by Customs and Border Protection. Two weeks ago, a teenage mother with a premature baby was found in a Border Patrol processing center in McAllen, Texas after being held for nine days by the government.

Government rules call for children to be held by the Border Patrol in their short-term stations for no longer than 72 hours before they are transferred to the custody of the U.S. Department of Health and Human Services, which houses migrant youth in facilities around the country through its Office of Refugee Resettlement while authorities determine if they can be released to relatives or family friends.

Customs and Border Protection referred AP's questions about the Clint Facility to the Office of Refugee Resettlement, which said Monday that 249 children previously held in Clint would be moved to the agency's network of shelters and other facilities by Tuesday.

'(Unaccompanied children) are waiting too long in CBP facilities that are not designed to care for children,' ORR spokeswoman Evelyn Stauffer said. 'These children should now all be in HHS care as of Tuesday.'