Protesters interrupted acting Homeland Security Secretary Kevin McAleenan's speech at an immigration conference on Monday, prompting the official to get visibly unsettled, abruptly end his speech, and walk off stage.

The demonstrators quickly drowned out McAleenan's speech as he stepped to the lectern to deliver his remarks at the Georgetown University-hosted event, shouting, "Immigrants are under attack. What do we do? Stand up, fight back" and "Children are under attack. What do we do? Stand up, fight back." Protesters also held a banner that read, "Hate is not normal."

The demonstrators appeared to shout the names of multiple migrants who have died in immigration custody in recent months, including several children. The treatment of immigrants at border facilities has roiled McAleenan's tenure since he took over the agency this past April following then-DHS chief Kirstjen Nielsen's resignation.

The event's moderator then tried to quell the shouting, which drew favorable applause from some members of the audience. McAleenan then attempted to persuade the audience to no avail.

"As a career law enforcement professional, I've decided my career to protecting the right to free speech and all the values we hold dear in America from all threats, so we'll go ahead and try one more time," he said⁠— to which a protester yelled out "bullsh—t."

After moderators tried again to temper the demonstration, McAleenan restarted his speech but soon walked off stage when the chanting began once more.

McAleenan's predecessor was also subject to protests over the Trump administration's hard-line immigration policies, especially the practice of separating migrant children from their parents at the border. Last year, Nielsen was interrupted by protesters during a dinner at an upscale Mexican restaurant in Washington.

DHS rebuked the protesters in a statement released later on Monday.

"The First Amendment guarantees all Americans the right to free speech and assembly," the department said in an unsigned statement. "Unfortunately that right was robbed from many who were scheduled to speak and attend today’s event at Georgetown. Unfortunately the Acting Secretary and the audience did not get the opportunity to engage in a robust dialogue this morning due to the disruptions of a few activists."

The president of the Migration Policy Institute, one of event's organizers, also expressed "regret" about the hecklers.

"In a democracy, it is important to hear from all sides on public policy issues, including from those who are instrumental in developing and implementing policy, whether or not we agree with them, and MPI remains committed to that belief," said Andrew Selee. "By drowning out the Secretary's remarks, the protesters deprived immigration attorneys, service providers, journalists, advocates, business leaders, law students, and many others in the public who were in the audience from hearing his point of view and engaging in a meaningful dialogue."