There were reports Wednesday some of the insurrectionists were prepared to occupy the Capitol throughout the night, and these zip tie pics suggest they were prepared to hold people -- perhaps Congressional leaders -- against their will.

At least 2 different men were seen holding the zip ties -- commonly used as disposable handcuffs -- inside the U.S. Senate Chamber after members of Congress were forced to flee due to the security breach.

On top of this ... we already know many members of the mob that invaded the Capitol were armed, willing to bust into offices and take whatever they wanted, and someone even left behind the threat, "Murder the media," by scratching it on a door.

And, don't forget -- D.C. cops also found explosives near the building that were safely detonated.

It's all potentially crucial evidence, as it could show President Trump wasn't spontaneously urging his amped-up followers to "show strength" and simply march to the Capitol -- it could show the attack was all a premeditated plan.

That means more serious charges for all the rioters, and possibly, for Trump once he's out of office.