She said Secret Service member James Murray would take over as director in May.
U.S. Secret Service Director Randolph "Tex" Alles was sacked Monday, and U.S. Citizenship and Immigration Services Director Lee Cissna, DHS undersecretary for management Claire Grady and DHS general counsel John Mitnick are also leaving the administration.
"These two reports are deeply troubling, raising additional concerns about how the White House is handling Secret Service security matters at Mar-A-Lago and elsewhere".
And after the security breach, Trump praised the Secret Service.
Alles' reported ouster occurred less than a day after Homeland Security Secretary Kristjen Nielsen abruptly announced her resignation, which came amid pressure and growing dissatisfaction from Trump and immigration hard-liners in the White House.
The decision to force out Alles comes just days after a woman was arrested at the president's Mar-a-Lago club with Chinese passports and computer and cell phone malware after she made it past a checkpoint.
Speaking anonymously, three administration officials told the Associated Press Alles' departure stemmed from a personality conflict within the agency.
One anonymous official tells CNN that the Trump White House is undergoing something close to a full cleansing of people working at important national security positions.
But administration officials told Fox News on Sunday that Nielsen's background in cybersecurity made her a poor fit to handle border issues, while McAleenan best fits Trump's requirement of being the "toughest cop" on the frontier. Alles reported to Nielsen.
President Donald Trump instructed his acting chief of staff, Mick Mulvaney, to fire Alles.
Alles - a 35-year veteran of the Marines - had also had leadership posts in Customs and Border Protection and led the agency's Air and Marine Operations.
L. Francis Cissna, director of the US Citizenship and Immigration Services agency, and department General Counsel John Mitnick also are expected to be out of their jobs soon, CNN reported.