(CNN) -- Federal investigators are chasing thousands of leads in twin efforts to prosecute people involved in last week's attack on the US Capitol and to try to prevent feared follow-up attacks in Washington and around the country.

But while the FBI has opened more than 160 case files in the six days since pro-Donald Trump rioters breached the US Capitol building, officials acknowledged Tuesday that the evidence gathered so far "is just the tip of the iceberg."

"People are going to be shocked by some of the egregious contact that happened in the Capitol," acting US Attorney Michael Sherwin said.

At the same time, officials from the FBI and Department of Justice sought to reassure the American public Tuesday that they are up to the task on both fronts during a press conference that also laid bare the enormity of the challenge currently facing law enforcement agencies involved in both efforts.

"The FBI is quite familiar with large-scale, complex investigations ... we are up to the challenge," FBI Washington DC field office assistant director Steven D'Antuono said.

Sherwin echoed that point, telling reporters "The scope and the scale of this investigation into these cases are really unprecedented not only in FBI history but probably DOJ history in which essentially the Capitol grounds outside and inside are essentially a crime scene."

"It is not going to be solved in the coming months," he added.

FBI Director Christopher Wray did not attend the news conference.

The Justice Department has already charged 70 cases, and Sherwin said he believes that number will grow into the 100s, and already arrested individuals may face more serious crimes.

The FBI is tracking money, travel records, movements of people and communications in addition to following tips from the public and footage and photos from the scene last Wednesday.

D'Antuono also said agents are still investigating whether participants in the riot were looking to take members of Congress as hostages.

D'Antuono noted the FBI is pursuing information about a person or people who helped to plant pipe bombs outside the Republican and Democratic headquarters last week.

He said the bombs were real and had timers.

"We don't know exactly why they didn't go off."

CNN's Katelyn Polantz contributed to this report.

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