In a day filled with shocking images, one of the most startling was a mob of President Trump's supporters surging into the U.S. Capitol with relative ease.
Armed with pro-Trump banners, the rioters far outnumbered and swiftly overwhelmed the U.S. Capitol Police as they charged up the steps, smashed windows, broke into the Senate chamber and occupied offices, including the one belonging to House Speaker Nancy Pelosi.
Police needed hours to drive them out, and the toll was substantial. According to police, four people died, including one woman shot dead by Capitol Police, and three who died on the Capitol grounds from unspecified "medical emergencies." More than 50 people were arrested, at least a dozen police were injured, and officers confiscated guns, pipe bombs and Molotov cocktails.
With so many police and security agencies present in Washington, why were so few resources deployed in advance?
Violence was considered a distinct possibility. This was the third major rally in recent weeks to support President Trump's fictional claim that the presidential election was rigged. The most recent one in December included fights in the streets, with several people stabbed.
Washington Mayor Muriel Bowser announced Tuesday that the D.C. Metropolitan Police Department would be the lead agency and would coordinate with the Capitol Police, the U.S. Park Police and the U.S. Secret Service.
"To be clear, the District of Columbia is not requesting other federal law enforcement personnel and discourages any additional deployment without immediate notification to, and consultation with, MPD if such plans are underway," Bowser wrote in a letter to the Justice Department earlier this week.
Bowser requested, and received, a limited force from the D.C. National Guard. They numbered 340, though they were unarmed and their job was to help with traffic flow — not law enforcement — which was to be handled by D.C. police.
But as the mob left Trump's rally near the White House and soon reached the western side of the Capitol, it quickly became clear that there wasn't a sufficient security presence to stop them.
"We see this huge crush of people coming down Pennsylvania Ave. toward the Capitol," said NPR's Hannah Allam, who covered the riot.
"We followed the crowd as it goes up to the Hill, toward the Capitol. There's scaffolding set up for the inauguration already," she added. "But as far as protection, all we really saw were some mesh barriers, some metal fencing and only a small contingent of Capitol Police. And we watched them being quickly overwhelmed."
In a video taken inside the Capitol, a lone policeman tries to hold back the mob with a baton. But he eventually retreats up the stairs until he finds additional colleagues, though they still remain outnumbered.
A troubling precedent
Bowser's approach to security was clearly influenced by events last summer when demonstrators took to the streets near the White House to protest the killing of George Floyd in Minneapolis and other police abuses.
At the time, President Trump called for a strong show of force, including active-duty military personnel deployed on the streets of the nation's capital. While Pentagon officials eventually talked Trump out of that demand, federal security forces were called in, including guards from the U.S. Bureau of Prisons who did not wear identifying name tags.
The response was widely seen as heavy handed, and included security forces driving out peaceful protesters to clear the way for a photo-op Trump wanted at a church near the White House. Bowser wanted to avoid a similar scenario this time, particularly by federal forces that do not answer to the D.C. government.
The full contingent of the D.C. National Guard, about 1,100 strong, was not mobilized until after the immediate crisis had passed on Wednesday evening. They are being joined by Guard members and other law enforcement personnel from Virginia, Maryland and New Jersey.
D.C. is known for its fiefdoms of law enforcement agencies, and that was reflected in the four agencies involved in security on Wednesday. The MPD has jurisdiction on city streets; the Park Police on the Ellipse, where Trump's rally took place; the Secret Service in the vicinity of the White House; and the Capitol Police on the Capitol complex.
The coming weeks
Bowser imposed an overnight curfew and has declared a public emergency that extends for 15 days, through Joe Biden's presidential inauguration on Jan. 20.
Due to the pandemic, the gathering at Biden's inauguration will be quite small and therefore place fewer demands on security personnel. Still, security officials are expected to err on the side of too much, rather than too little, security over the next two weeks.
Meanwhile, some in Congress are demanding an accounting of what took place Wednesday.
"There was not supposed to be anyone near the Capitol," said Rep. Tim Ryan (D-Ohio), who chairs a committee that oversees the Capitol Police. "Those were illegal acts, and those people should have been immediately arrested."
When the Senate resumed its session on Wednesday evening, New Jersey Democratic Sen. Cory Booker observed that the last time the Capitol had come under such an attack was when British forces set it on fire in 1814.
Greg Myre is an NPR national security correspondent. Follow him @gregmyre1.