HOUSTON — The acting head of US Customs and Border Protection resigned Tuesday amid an uproar over the discovery of migrant children being held in pitiful conditions at one of the agency's stations in Texas.

Acting Commissioner John Sanders' departure deepened the sense of crisis and added to the rapid turnover inside the agencies responsible for enforcing President Donald Trump's hardline immigration priorities as the US deals with record numbers of migrant families coming across the border.

In a message to employees, Sanders said he would step down on July 5. He did not give a reason for leaving.

"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.

Hours after Sanders' departure became public, two officials told The Associated Press that he was being replaced by Mark Morgan, who was named acting director of US Immigration and Customs Enforcement just last month. The officials were not authorized to speak publicly about the move and declined to be identified.

AP