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 a defense official and two people familiar with the matter.

Capitol Police had planned for a free speech demonstration and didn't need more help, those three told The Associated Press. The police weren't expecting what actually happened — an insurrection.

But the Capitol ended up being overrun, overwhelming a law enforcement agency sworn to protect the lawmakers inside. Four protesters died, including one who was shot inside the building.

There had been plenty of warnings. Plenty of time to prepare. Plenty of money to do it.

The failure raised serious questions over security at the Capitol and the treatment of mainly white Trump supporters who were allowed to roam through the building, compared with the Black and brown protesters across the country who demonstrated last year over police brutality.

By the day after the rampage, the House sergeant-at-arms, the chief security officer for the House of Representatives, had resigned and House Speaker Nancy Pelosi, D-Calif., had called for the resignation of the Capitol Police chief.

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

Sen Chuck Schumer, D-N.Y., the incoming majority leader, said he will fire the Senate sergeant-at-arms.

The Capitol had been closed to the public since March because of the COVID-19 pandemic, which killed more than 350,000 people in the United States. In normal times, the building is open to the public and lawmakers pride themselves on their availability to their constituents.

It's not clear how many Capitol Police offers were on-duty Wednesday. There are 2,300 officers who patrol 16 acres of ground and protect the 435 House members, 50 senators and their staffs. By example, the city of Minneapolis has about 840 uniformed officers for a population of 425,000 across more than 6,000 acres of land.

The Capitol Police has an operating budget of USD 460 million and has experience with high-security, high-stakes moments. It is used to managing large crowds and large events such as the inauguration, the State of the Union and mass demonstrations.

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.