'It broke me': Capitol officer describes recurring trauma of Jan. 6 attack

Two years after the Jan. 6 attack, U.S. Capitol Police officer Harry Dunn says he's still dealing with the emotional scars from that day.

Dunn, who struggled to defend the Capitol amid the hours of violence, described how his PTSD flared up this past fall.

"That moment in time hit me so hard is because I have made such good progress, to heal and be able to deal with these emotions and these feelings in a healthy manner and, you know, I could walk in and not be fazed by seeing somebody in a MAGA hat or a Confederate flag …. I made such good progress," Dunn said in an interview with ABC News Chief Justice Correspondent Pierre Thomas.

"But it was all just like out of nowhere just ripped away from me. And it wasn't a specific incident that caused it. Man, I thought I had this under control. I beat this," he said. "But no, it literally just came out of nowhere and it broke me, you know it broke me."

The interview will air on ABC's "This Week with George Stephanopoulos" on Sunday.