As Americans watched Wednesday, an angry mob of mostly white people stormed the U.S. Capitol, seeming to overwhelm Capitol Police, who struggled to contain the violence. Officers yielded to the mob in some cases and allowed crowds of supporters of President Donald Trump into the halls of Congress as its members were affirming that President-elect Joe Biden had won the November election.
Many people saw in the images and videos that poured out of the Capitol more than a disturbing breach of security by people who believe Trump's baseless claims of election fraud. They said they saw white privilege and double standards and questioned whether the police response would have been the same had the rioters been Black or brown people or their allies.
"No one can tell me that if it had been a group of Black Lives Matter protesters yesterday that they wouldn't have been treated very differently than the mob that stormed the Capitol," Biden said Thursday. "We all know that's true — and it's unacceptable."
There were many such observations Wednesday as law enforcement officers appeared to treat pro-Trump rioters with restraint — even as they broke through barricades, windows and doors, strolled through the halls of the Capitol and posed in Senate chambers — that was not afforded to peaceful demonstrators during the protests in Washington, D.C., and elsewhere over the summer following the death of George Floyd in Minneapolis police custody.
By contrast, police used pepper spray, tear gas and what appeared to be rubber bullets against people protesting unprovoked police violence against African Americans near the White House in May. In one encounter, police with support from the National Guard stormed into a peaceful protest outside the White House so Trump could walk across the street, where the protesters had been assembled, to pose for photos holding a Bible in front of a church.
The deferential treatment to the white rioters came even after Trump warned Black Lives Matter protesters in June that they would face a minimum of 10 years in prison for vandalizing or damaging federal buildings.
"I think it's absolutely true that the insurgents yesterday were treated with much more care than the folks who participated in the Black Lives Matter protests," said Keneshia Grant, an associate professor of political science at Howard University. "What we saw was a system of law enforcement that's designed to protect certain people."
Attica Scott, a Democratic state representative in Kentucky, remembered what it was like to be on the wrong side of mistreatment. She and her 20-year-old daughter, Ashanti, were arrested on felony charges in Louisville in September during a protest against the police killing of Breonna Taylor in a botched raid. The charges have since been dropped.
Wednesday's riot at the Capitol was an unfriendly reminder of the country's racial double standards.
"It just was a painful reminder to me that many of us live in a very different country than many of the white people that we know," Scott said.
She and her daughter had been walking to a church when they were arrested, Scott said.
Four people died during the Capitol riots, including a woman who authorities said was fatally shot by Capitol Police. Three other people died after unspecified "medical emergencies," Washington Police Chief Robert Contee said. Pipe bombs were found at the headquarters of both the Republican and the Democratic national committees, Contee said.
Ronnie Dunn, an associate professor of urban studies at Cleveland State University, said the show of force was different Wednesday.
"The use of force was absent. Had that been Black protesters storming the Capitol, we would have seen a completely different response," he said. "I doubt they would have breached the inner chambers."
Dunn said he was taken aback by law enforcement's seeming unpreparedness considering that Trump "has been calling for this" for some time. He said the public deserves to know how the rioters managed to walk onto the Senate floor.
"Race is a factor. Let's just be candid about it," he said. "This is the epitome of white privilege or white supremacy — the notion that they have the right or dominion to go into the Capitol and overthrow the results of a fair and free election and the will of the people."
Rep. Maxine Waters, D-Calif., also demanded answers.
"We must investigate the security breach at the Capitol today," Waters tweeted Wednesday, adding that she had warned the Democratic caucus and had had an hourlong conversation with the police chief four days previously. "He assured me the terrorists would not be allowed on the plaza & Capitol secured."
Joseph Giacalone, a retired New York police sergeant who teaches at the John Jay College of Criminal Justice at the City University of New York, said there was an obvious lack of planning by Capitol Police, especially considering that protests had been planned in advance and that law enforcement agencies knew that the far-right group Proud Boys, whom Trump told to "stand back and stand by" during the first presidential debate, were likely to attend.
Giacalone said there were too few personnel to stop or deter rioters and that there was "a stark difference in preparation between what occurred during the summer and what occurred yesterday."
In a statement Thursday morning, Capitol Police Chief Steven Sund defended the department's response, saying officers "acted valiantly when faced with thousands of individuals involved in violent riotous actions."
More than 50 Capitol and D.C. police were injured, including several who were hospitalized with serious injuries, Sund said.
Sund said that the "violent attack" Wednesday was unlike any he had ever experienced in his 30 years in law enforcement in Washington, D.C., and that "a thorough review would be conducted of this incident, security planning and policies and procedures."
Sund announced later on Thursday that he intends to resign, effective Jan. 16, amid criticism of his department's response.
Washington's mayor called the police response "a failure."
This story first appeared on NBCNews.com.