U.S. Rep. Jason Crow led over 100 members of the House of Representatives on Thursday in asking Congress’ independent auditing agency to investigate law enforcement’s preparation and response to the mob invasion of the U.S. Capitol this week.

“We write to you today with grave urgency over the acts of insurrection that occurred yesterday at the United States Capitol complex and the unprecedented incitement and security failures that directly led to the overrun of government offices by terrorists,” reads the letter to Gene L. Dodaro, head of the U.S. Government Accountability Office.

U.S. Reps. Diana DeGette and Ed Perlmutter also signed the letter.

Describing the actions of the violent supporters of President Donald Trump, the request to Dodaro noted that people in the Capitol evacuated, sheltered in place and called loved ones during the siege.

The topics for investigation include the adequacy of preparations for that day’s election protest rally, the effectiveness of the federal and local response, and the impact of “rhetoric by government and elected officials that contributed to or led to the insurrection.”

The letter raised the possibility of a coordinated effort to limit law enforcement’s response. Gov. Larry Hogan, R-Md., disclosed on Thursday that he had mobilized the state’s National Guard upon request from Democratic congressional leaders, but federal officials within the executive branch refused to authorize the deployment until 90 minutes later.

Also of interest to members: the difference in response to this week’s rioters “compared to other large gatherings in Washington, D.C., in the past four years.”

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Social media has been flooded with comparisons of the relatively tame law enforcement reaction to the largely white Trump mob to the overwhelming police response during some of the Black Lives Matter protests in the summer of 2020. President-elect Joe Biden also agreed with that critique.

“No one can tell me that if it had been a group of Black Lives Matter protestors yesterday that they wouldn’t have been treated very differently than the mob that stormed the Capitol. We all know that’s true — and it’s unacceptable,” he tweeted.

Five people — a Capitol Police officer who was struck with a fire extinguisher during the riot, a rioter who was shot by Capitol Police and three other Trump supporters who were trampled and suffered a heart attack and a stroke — died in the attack on the Capitol.

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Numerous Trump supporters have been arrested and face federal charges.

The fallout wasn’t limited to the rioters; the Capitol’s three top security officials resigned under pressure from lawmakers over failures that allowed the breach that disrupted Congress’ acceptance of Electoral College votes that sealed Joe Biden’s victory over Trump.

Senate Majority Leader Mitch McConnell accepted the resignation of Senate Sergeant-at-Arms Michael Stenger late Thursday.

Earlier Thursday, U.S. Capitol Police Chief Steven Sund resigned, with House Speaker Nancy Pelosi demanding he step down.

The Associated Press contributed to this report.