Tense officers pointing guns, lawmakers with gas masks, camouflaged protesters smashing windows -- this was the day that President Donald Trump's bid to overturn the US election went "wild."

Inside the great domed US Capitol building, images emerged of a scene resembling something from a coup d'etat or terrorist attack.

Supporters of US President Donald Trump enter the US Capitol's Rotunda
Supporters of US President Donald Trump enter the US Capitol's Rotunda AFP / Saul LOEB

A mob, waving Trump's blue flags and wearing his red campaign hats, stormed through, making it right into the debating chamber.

And the rioters quickly accomplished their main goal: halting the ceremony that had just got underway to certify Democrat Joe Biden's election win over Trump back in November.

Legislators were given gas masks to protect themselves against tear gas as they rushed to safety, abandoning the ceremony.

A supporter of US President Donald Trump sits inside the office of US Speaker of the House Nancy Pelosi
A supporter of US President Donald Trump sits inside the office of US Speaker of the House Nancy Pelosi AFP / SAUL LOEB

In the House chamber, a viral photo on Twitter showed plainclothes security men aiming pistols point blank through the smashed window of a door to block intruders.

One person, not identified by authorities, was wounded by a gunshot inside the Capitol building, an emergency response source told AFP. According to US media reports, the victim later died.

A supporter of US President Donald Trump wears a gas mask as he protests after storming the US Capitol
A supporter of US President Donald Trump wears a gas mask as he protests after storming the US Capitol AFP / Brendan SMIALOWSKI

And as quickly as members of Congress could get out, protesters got in.

Some even occupied the office of House Speaker Nancy Pelosi, sitting mockingly at a desk. Others posed for pictures, like conquering troops, in the Senate chamber.

Trump had promised his supporters that Wednesday would be a "wild" day for the nation's capital.

Supporters of US President Donald Trump rampaged through Congress
Supporters of US President Donald Trump rampaged through Congress AFP / ROBERTO SCHMIDT

It was.

"I've not seen anything like this since I deployed to Iraq," Mike Gallagher, a Republican lawmaker and military veteran, told CNN.

Supporters of US President Donald Trump protest in the US Capitol Rotunda
Supporters of US President Donald Trump protest in the US Capitol Rotunda AFP / SAUL LOEB

After several hours of mayhem, Trump issued a short video on Twitter calling on people to "go home."

US President Donald Trump's supporters clash with police and security forces
US President Donald Trump's supporters clash with police and security forces AFP / Joseph Prezioso

But there was no indication of regret, much less condemnation of the violence.

Instead, Trump then used his White House video to repeat his false, incendiary claims that the presidential election "was stolen from us."

"We love you. You're very special," he congratulated the mob.

Trump supporters smash media equipment outside the US Capitol
Trump supporters smash media equipment outside the US Capitol AFPTV / Agnes BUN

Ever since November, Trump has been trying to get the election overturned.

The only difference is that two weeks before Biden is due to be inaugurated -- at the very spot where protesters rampaged outside the Capitol on Wednesday -- Trump's tactics are becoming cruder.

Initially he tried in court, going all the way to the Supreme Court with lurid, often half-baked claims of mass election fraud. Every time, judges threw his cases out for lack of supporting evidence.

Trump then tried to get local election officials to "find" him extra votes, as he put it in a phone call with one in Georgia.

Finally, Trump tried to threaten his vice president, Mike Pence, openly telling him somehow to blow up Wednesday's formal ceremony.

Pence, infuriating Trump, retorted that he had no constitutional leeway to mess around with the rules. He showed up to Congress and began the procedure.

Yet Trump's supporters were up to the job.

They got a final pep talk from their leader earlier Wednesday, when Trump encouraged thousands of people on the National Mall to march on Congress.

Within minutes, they were pouring up the Capitol steps.

Television footage showed men, some in military gear, smashing a window and climbing through. Other groups clambered up on the roofs of black official vehicles parked outside Congress, abandoned by their drivers.

"USA, USA, USA," Trump supporters chanted as they fought against police, hurling poles, metal pipes and other debris.

"They can't stop us all," a man with a megaphone called to the crowd, urging people to rush the Capitol entrances.

One of the participants, Jordan Shackleford, 25, insisted that he was on the side of right. He'd driven all the way from Oklahoma to support Trump.

"They rigged the election," he insisted.

As the day ended, police tried to clear the last stragglers before a draconian Washington curfew kicked in.

But the menace lingered.

Spotting a cordoned off pen holding journalists trying to cover the scenes outside Congress, a group of about 45 aggressive Trump supporters rushed in, knocking cameras to the ground and yelling "traitors."