Capitol police officers stand outside of fencing that was installed around the exterior of the Capitol grounds, Thursday, Jan. 7, 2021 in Washington. The House and Senate certified the Democrat's electoral college win early Thursday after a violent throng of pro-Trump rioters spent hours Wednesday running rampant through the Capitol. A woman was fatally shot, windows were bashed and the mob forced shaken lawmakers and aides to flee the building, shielded by Capitol Police. (AP Photo/John Minchillo)

WASHINGTON (AP) — Three days before supporters of President Donald Trump rioted at the Capitol, the Pentagon asked the U.S Capitol Police if it needed National Guard manpower. And as the mob descended on the building Wednesday, Justice Department leaders reached out to offer up FBI agents. The police turned them down both times, according to senior defense officials and two people familiar with the matter.

Despite plenty of warnings of a possible insurrection and ample resources and time to prepare, the Capitol Police planned only for a free speech demonstration.

Still stinging from the uproar over the violent response by law enforcement to protests last June near the White House, officials also were intent on avoiding any appearance that the federal government was deploying active duty or National Guard troops against Americans.

The result is the U.S. Capitol was overrun Wednesday and officers in a law enforcement agency with a large operating budget and experience in high-security events protecting lawmakers were overwhelmed for the world to see. Four protesters died, including one shot inside the building.

The rioting and loss of control has raised serious questions over security at the Capitol for future events. The actions of the day also raise troubling concerns about the treatment of mainly white Trump supporters, who were allowed to roam through the building for hours, while Black and brown protesters who demonstrated last year over police brutality faced more robust and aggressive policing.

“This was a failure of imagination, a failure of leadership,” said Houston Police Chief Art Acevedo, whose department responded to several large protests last year following the death of George Floyd. “The Capitol Police must do better and I don’t see how we can get around that.”

Acevedo said he has attended events on the Capitol grounds to honor slain police officers that had higher fences and a stronger security presence than what he saw on video Wednesday.

Army Secretary Ryan McCarthy said that as the rioting was underway, it became clear that the Capitol Police were overrun. But he said there was no contingency planning done in advance for what forces could do in case of a problem at the Capitol because Defense Department help was turned down. “They’ve got to ask us, the request has to come to us,” said McCarthy.

Capitol Police Chief Steven Sund was planning to resign, as was the House sergeant-at-arms, the chief security officer for the House of Representatives. Sen. Chuck Schumer, D-N.Y., the incoming majority leader, said he will fire the Senate sergeant-at-arms.

“There was a failure of leadership at the top,” House Speaker Nancy Pelosi said.

The U.S. Capitol had been closed to the public since March because of the COVID-19 pandemic, which has now killed more than 360,000 people in the U.S. But normally, the building is open to the public and lawmakers pride themselves on their availability to their constituents.

It is not clear how many officers were on-duty Wednesday, but the complex is policed by a total of 2,300 officers for 16 acres of ground who protect the 435 House representatives, 100 U.S. senators and their staff. By comparison, the city of Minneapolis has about 840 uniformed officers policing a population of 425,000 in a 6,000-acre area.

There were signs for weeks that violence could strike on Jan. 6, when Congress convened for a joint session to finish counting the Electoral College votes that would confirm Democrat Joe Biden had won the presidential election.

On far-right message boards and in pro-Trump circles, plans were being made.

The leader of the far-right extremist group Proud Boys was arrested coming into the nation’s capital this week on a weapons charge for carrying empty high-capacity magazines emblazoned with their logo. He admitted to police that he had made statements about rioting in tWashington, local officials said.