WASHINGTON -- The police were badly outnumbered.

Only a few dozen guarded the West front of the U.S. Capitol when they were rushed by thousands of pro-Trump demonstrators bent on breaking into the building.

Armed with metal pipes, pepper spray and other weapons, the mob pushed past the thin police line, and one rioter hurled a fire extinguisher at a officer, according to video widely circulated on YouTube.

"They're getting into the Capitol tonight! They're getting in," the man filming shouts in delight.

They breached the line moments later, and rioters soon broke into the building, taking over the House and Senate chambers and running wild in Statuary Hall and other hallowed symbols of democracy. The mob ransacked the place, smashing windows and waving Trump, American and Confederate flags. The lawmakers who were voting to affirm President-elect Joe Biden's victory were forced into hiding for hours.

Throughout the melee, police officers were injured, mocked, ridiculed and threatened. Thursday night from injuries suffered during the riot. The melee was instigated by a mob of supporters of President Donald Trump who have professed their love of law enforcement and derided the mass police reform protests that shook the nation last year following the police killing of George Floyd in Minneapolis.

"We backed you guys in the summer," one rioter screamed at three officers backed against a door by dozens of men screaming for them to get out of their way. "When the whole country hated you, we had your back!"

The rampage shocked the world and left the country on edge, forcing the resignations of three top Capitol security officials over the failure to stop the breach. Lawmakers have demanded a review of operations and an FBI briefing over what they called a "terrorist attack."

Sicknick was the fifth person to die because of the Capitol violence.

One rioter, a woman from California, was shot to death by Capitol Police, and three other people died after "medical emergencies" related to the breach, including at least who died of an apparent heart attack.

Sicknick, 42, was hit in the head with a fire extinguisher during a struggle, two law enforcement officials said, although it was not clear if he was the officer shown in the video. The officials could not discuss the ongoing investigation publicly and spoke to The Associated Press on condition of anonymity.

Another disturbing video shows a bloodied police officer screaming for help as he's crushed by rioters inside the Capitol building. The young officer is pinned between a riot shield and metal door. Bleeding from the mouth, he cries out in pain and screams, "Help!"

Other images show police completely overwhelmed by rioters who shoved, kicked and punched their way into the building. In one stunning video, a lone police officer tries to hold off a mob of demonstrators from cracking into the lobby. He fails.

Trump-supporters attacked police with pipes, sprayed irritants and even planted live bombs found in the area.

Sicknick's family said Friday that he had wanted to be a police officer his entire life. He served in the New Jersey Air National Guard before joining the Capitol Police in 2008. Many details regarding the incident remain unknown, and Sicknick's family urged the public and news media not to make his death a political issue.

Still, the riot -- and Sicknick's death -- focused renewed attention on Capitol Police, a force of more than 2,300 officers and civilian employees that protects the Capitol, lawmakers, staff and visitors. The agency has an annual budget of about $515 million.

Three days before the riot, the Pentagon offered National Guard manpower. And as the mob descended on the building Wednesday, Justice Department leaders reached out to offer up FBI agents. Capitol Police turned them down both times, according to senior defence officials and two people familiar with the matter.

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

Like many other agencies, the Capitol Police have been hit hard by COVID-19, with frequent schedule changes for officers and many forced to work overtime to fill out rosters. The pandemic has put the police under strain going into the new session of Congress and the Jan. 20 inauguration of President-elect Joe Biden.

Capitol Police Chief Steven Sund, who resigned Thursday under pressure from House Speaker Nancy Pelosi and other congressional leaders, defended his department's response, saying officers "acted valiantly when faced with thousands of individuals involved in violent riotous actions." Two other top security officials, Senate Sergeant at Arms Michael Stenger and House Sergeant at Arms Paul Irving, also resigned.

By Friday, prosecutors had filed 14 cases in federal district court and 40 others in the District of Columbia Superior Court for a variety of offences ranging from assaulting police officers to entering restricted areas of the U.S. Capitol, stealing federal property and threatening lawmakers. Prosecutors said additional cases remained under seal, dozens of other people were being sought by federal agents and the U.S. attorney in Washington vowed that "all options were on the table" for charges, including possibly sedition.

Among those charged was Richard Barnett, an Arkansas man who was shown in a widely seen photo sitting in Pelosi's office with his boots on the desk. He also wrote a disparaging note to Pelosi. Acting Attorney General Jeffrey Rosen called the photo of Barnett a "shocking image" and "repulsive.'

"Those who are proven to have committed criminal acts during the storming of the Capitol will face justice," Rosen said.

Also charged was a West Virginia state lawmaker who posted videos online showing himself pushing his way inside the Capitol, fist bumping with a police officer and then milling around the Rotunda as he shouted "Our house!" The lawmaker, Derrick Evans, was arrested by the FBI at his home on Friday and charged with entering restricted federal property.

Gus Papathanasiou, chairman of the Capitol Police Officers' Union, said he was "incredibly proud of the individual officers whose actions protected the lives of hundreds of members of Congress and their staff."

Once the breach of the Capitol building was inevitable, officers prioritized lives over property, leading people to safety, he said. "Not one member of Congress or their staff was injured. Our officers did their jobs. Our leadership did not. Our law enforcement partners that assisted us were remarkable."

Rep. Tim Ryan, D-Ohio, who leads a subcommittee that oversees the Capitol Police budget, said Friday that rank-and-file officers "were put in a incredibly dangerous situation. And that's really where my frustration comes in."

Sund and other leaders are charged with protecting lawmakers, "but also making sure that the rank-and-file members are put in situations where they're as safe as possible and they have the support that they need. And that clearly isn't the case," Ryan said.

Pelosi ordered flags at the Capitol lowered to half-staff in Sicknick's honour.

------

Associated Press writers Lisa Mascaro in Washington, Nomaan Merchant in Houston and Derek Karikari in New York contributed to this report.