During the briefing, Michael Sherwin, Acting US Attorney for Washington, said: "We have already opened more than 170 subject files, meaning these individuals have been identified as potential persons that committed crimes on the Capitol grounds.
"Of those 170 cases that have already been opened – and I anticipate that's going to grow to the hundreds in the coming weeks – we've already charged over 70 cases. And again, that number, I suspect, is going to grow into the hundreds."
Sherwin said the "range of criminal conduct" being investigated was "unmatched" and "mind-blowing".
"We're looking at everything from criminal trespass, to theft of mail, to theft of digital devices within the Capitol, to assault on local officers, federal officers, to the theft of potential national security information, to felony murder, and even civil rights and excessive force investigations," he said.
"Regardless of if it was just a trespass in the Capitol, or if someone planted a pipe bomb, you will be charged and you will be found."
He said the FBI was looking at "significant felony cases tied to sedition and conspiracy". Such charges can bring jail terms of up to 20 years.
Steven D'Antuono, from the FBI's Washington DC field office, spent some time describing the challenge of distinguishing genuine threats from people making empty threats on the internet.
"To be clear, the brutality the American people watched with shock and disbelief on the sixth will not be tolerated by the FBI. The men and women of the FBI will leave no stone unturned in this investigation," D'Antuono said.
"The significance of this investigation is not lost on us. This is a 24/7, extensive operation into what happened that day.
"The FBI receives enormous amounts of information and intelligence, and our job is to determine the credibility and viability of it.
"We have to separate the aspirational from the intentional, and determine which of the individuals saying despicable things on the internet are just practising keyboard bravado, [and which] have the actual intent to do harm.
"As offensive as a statement can be, the FBI cannot open an investigation without a threat of violence or alleged criminal activity."