From CNN:

Evidence uncovered so far, including weapons and tactics seen on surveillance video, suggests a level of planning that has led investigators to believe the attack on the US Capitol was not just a protest that spiraled out of control, a federal law enforcement official says.

Among the evidence the FBI is examining are indications that some participants at the Trump rally at the Ellipse, outside the White House, left the event early, perhaps to retrieve items to be used in the assault on the Capitol.

A team of investigators and prosecutors are also focused on the command and control aspect of the attack, looking at travel and communications records to determine if they can build a case that is similar to a counterterrorism investigation, the official said.
[Post edited by JMHoo at 01/14/2021 07:23AM]