Following the intrusion of pro-Trump activists into Congress on Wednesday, an investigation is being conducted to understand what the security loopholes have been in and around the federal institution.
Lack of preparation, lack of anticipation, reinforcements too late, laxity ... The causes are potentially numerous.
How could such scenes of violence take place on the Capitol?
After the violence on Wednesday in Washington, where thousands of supporters of President Donald Trump burst into Congress, the United States is trying to answer this question.
>> VIDEO
- Donald Trump, "scandalized" by the violence, promises a "smooth" transition
Joe Biden denounces a form of laxity
Since Thursday, the police have been tracking those responsible for the overflows to hotels in the federal capital, but the investigation also relates to security breaches around the Capitol.
Even the future president of the country Joe Biden denounced in hollow a form of laxity towards the demonstrators.
Lack of preparation, lack of anticipation, the police, who did not see the size and the intentions of the crowd coming, are singled out.
>> Find Europe Matin in replay and podcast here
Questions about the behavior of some police officers
The Capitol Police are a force of 2,000 men, who found themselves on the front lines facing the demonstrators.
On Wednesday, the day of the violence, officers were not even in riot gear.
Questions also arise about the behavior of some police officers who, according to the images of a video, do not seem to really hold back the crowd.
Another policeman also posed for a photo with the protesters.
The police quickly found themselves overwhelmed, and the reinforcements took several hours to arrive.
Muriel Bowser, the mayor of Washington, had yet announced the presence of 35,000 national guards to secure the area.
>> IN IMAGES
- Pro-Trump intrusion on Capitol Hill: a look back at a day that shook American democracy
At the request of Nancy Pelosi, the Democratic leader of the House of Representatives, Capitol Police Chief Steven Sund announced his resignation Thursday, as did security officials from both Houses of Congress.
Finally, the difference in treatment with the "Black Lives Matter" protests of last summer shocks and moves many Democrats.
The National Guard was then mobilized to protect federal buildings.
A "double standard, two measures" unacceptable for Joe Biden.
On Friday, a police officer injured in clashes with protesters succumbed to his injuries.
Four protesters died during the incidents, including a woman hit by a police bullet.
For the other three deaths, the circumstances have not yet been clarified.