WASHINGTON, D.C. — FBI Director Christopher A. Wray called the Jan. 6 attack on the U.S. Capitol an act of “domestic terrorism” and defended the bureau’s handling of intelligence in the days before a mob of Donald Trump supporters stormed past police and threatened the lives of lawmakers.

“I was appalled that you, our country’s elected leaders, were victimized right here in these very halls. That attack, that siege, was criminal behavior. It is behavior that we, the FBI, view as domestic terrorism.”

Wray is facing questions from the Senate Judiciary Committee in a hearing delving into the bureau’s handling of threats posed by domestic terrorists and right-wing extremists in advance of the Capitol siege.

The FBI had come under fire from lawmakers and former Capitol security officials who said it didn’t share enough or adequate intelligence to help them prepare for the insurrection.

In response to questions from Sen. Richard Durbin, D-Ill., chairman of the committee, Wray pushed back on such criticism, saying his agency acted appropriately in how it shared raw intelligence Jan. 5 warning that President Trump supporters were gearing up for “war” in Washington.

“Our folks made the judgment to get that information to the relevant people as quickly as possible,” Wray said, adding that agents sent the warning via email, verbally at a command post and added it to a database available to law enforcement.

However, Wray said, “I do not consider what happened on Jan. 6, to be an acceptable result. And that’s why we’re looking so hard at figuring out how can the process be improved.”

Last week, three former Capitol security officials, who all resigned in the wake of the attack, and the Washington, D.C., police chief testified that the FBI and other federal agencies provided them with no concrete warnings of what was to come.

“None of the intelligence we received predicated what actually occurred,” former Capitol Police Chief Steven Sund testified Feb. 23 before a joint hearing of the Senate Rules and Homeland Security committees.

“We properly planned for a mass demonstration with possible violence,” Sund said. “What we got was a military-style, coordinated assault on my officers and a violent takeover of the Capitol building.”

Sund conceded that his agency had received an intelligence report Jan. 5 from the FBI warning that extremists were gearing up for “war” and threatening destruction at the Capitol and violence against members of Congress. But he said he didn’t see it until recent weeks. Saying it contained “raw” intelligence, Sund indicated the report likely would not have changed deployment plans.

Wray confirmed the report’s information was “raw, it was unverified.”

“In a perfect world, we would have taken longer to be able to figure out whether it was reliable, but we made the judgment” to pass it along,” Wray said, adding that “some of this is art, not science.”

Though lawmakers have focused attention on the FBI bulletin, there was plenty of other public evidence suggesting that Trump supporters were bent on disrupting the counting of electoral votes. News reports, for example, documented escalating rhetoric on social media sites and forums.

Trump was also active on Twitter and other platforms in promoting a “Stop the Steal” rally that drew thousands of his most diehard supporters to Washington on Jan. 6 — the day Congress was to certify the election results, which is normally a ceremonial exercise.

The rally was the culmination of the former president’s months-long, falsehood-filled campaign to overturn an election he lost to Joe Biden. Trump had been pushing for his vice president, Mike Pence, to unilaterally toss out some states’ votes for Biden, a power Pence did not have. Trump pressured Pence again in his rally speech and told supporters to head to the Capitol. “If you don’t fight like hell,” he said, “you’re not going to have a country anymore.”

Many heeded his call. Hundreds, many decked out in Trump campaign attire and waving Trump flags, stormed past police and into the Capitol. Trump was impeached by the House for inciting the riot, but the 57-43 vote in the Senate, though historically bipartisan, fell short of the two-thirds majority required for conviction.

The Justice Department has launched a sprawling investigation into the siege. Wray testified Tuesday that authorities have arrested more than 270 people on charges tied to the riot and had opened investigations in all but one of the bureau’s 56 field offices. The bureau has received nearly 300,000 tips tied to the assault, he said.

Wray noted the investigation has revealed that major players in the siege were members of right-wing militias or were white supremacists. He added, however, that a large number of attackers did not fit into any such categories.

A report released Tuesday by the George Washington University’s Program on Extremism found that 33 of about 260 people charged in the attack belonged to right-wing militia groups. Another 82 were part of “organized clusters” of friends and associates, the report said.

The report, based on a review of court filings, also found that a majority of those charged, 142, did belong to either militias or loosely organized groups.

Speaking more broadly about the threat of domestic terrorism, Wray said that the threat posed by lone wolves was “a challenge to get your arms around.”

“One of the things we struggle with, in particular, is that more and more of the ideologies, if you will, that are motivating some of these violent extremists are less and less coherent, less and less linear, less and less easy to kind of pin down,” Wray said. “In some cases it seems like people are coming up with their own sort of customized belief system.”

Wray testified that combating domestic terrorism is a top FBI priority, and the threat posed by extremists has grown. The FBI said it had arrested 180 people on charges tied to domestic terrorism in the fiscal year that ended Sept. 30, up from 107 the previous year. The Department of Homeland Security reported last year that violent white supremacy was the “most persistent and lethal threat in the homeland.”

The FBI director also rebutted conspiracy theories that anarchists — and not Trump supporters — were actually responsible for the attack.

“We have not to date seen any evidence of anarchist violent extremists or people subscribing to antifa in connection with the 6th,” Wray said, referring to leftist, anti-fascist groups.

Senate Democrats have expressed skepticism over how aggressively the FBI has battled right-wing extremists.

In a letter sent to Wray last week seeking information about domestic terror investigations, Democrats on the Senate Judiciary Committee criticized the agency for appearing to have taken steps during the Trump administration “to minimize the threat of white supremacist and far-right violence.”

Durbin said Tuesday that federal authorities needed to take the danger of such individuals and groups seriously.

“We need to be abundantly clear that white supremacists and other far-right extremists are the most significant domestic terrorism threat facing the United States today,” he said.