Transcript for FBI's Christopher Wray testifies on Capitol Riots
We're going to turn next to the investigation after the deadly riots at the capitol. FBI director Christopher WRAY testifying on capitol hill today, saying the FBI views the attack as an act of domestic terrorism. He was grilled about key intelligence and how soon it was and his blunt words tonight about who was responsible. Here's our chief justice correspondent Pierre Thomas now. Reporter: Tonight, in his first appearance before congress since the P January 6th insurrection, the FBI director was specific and blunt about who was responsible. Quite a number of what we would call militia violent extremists. The proud boys or the oath keepers. We've already identified individuals who advocate for what you would call white supremacy. Reporter: A fact confirmed by the only capitol police officer who has publicly described in detail the horror of that day. In a television exclusive with ABC news. It was a large number of people in that crowd that were racist. Reporter: Officer Dunn said that mob fought viciously. I'm exhausted, my shirt's drenched in sweat, pepper spray. I got blood and cuts on my knuckles. Reporter: And what of the conspiracies that it was really left wing radicals posing as trump supporters who attacked the capitol? Do you have any evidence that the capitol attack was organized by, quote, fake trump protesters? We have not seen evidence of that. Reporter: The FBI director was pressed on why a key piece of intelligence, warning that right wing radicals were coming to Washington to attack the capitol, did not result in more robust security. Why didn't the FBI sound the alarm? Reporter: WRAY says the information obtained the day before the insurrection was put in the hands of D.C. Officials. That information was quickly disseminated and communicated with our partners, including the U.S. Capitol police, including metro P.D. In three different Reporter: David, the FBI director says domestic terror cases have doubled since he took office, many involving radicals from the far right and white supremacists. 2,000 domestic terrorism cases under investigation right now. Pierre, thank you. We should note that interview you just showed there with that officer, more in a groundbreaking ABC news magazine. It debuts tonight, "Soul of a nation." A six-part series putting black life in America front and center. The authentic realities of black life in this country amid this moment of racial reckoning. We hope you'll watch, tonight 10:00 P.M. Eastern right here.
This transcript has been automatically generated and may not be 100% accurate.