The danger to the public and to law enforcement officers from explosive devices during expected upcoming protests "is substantial," the Federal Bureau of Investigation warned in a new awareness bulletin obtained by ABC News on Friday.

The document is full of photos of devices used in the last eight months against civilian and law enforcement targets during public demonstrations.

"Devices targeting infrastructure also increased following violent activity during this time period," the bulletin states.

The FBI now wants to make first responders aware of what has been deployed in the past and what they might encounter during protests linked to the presidential inauguration on Jan. 20.

"The danger posed to law enforcement officers and the general public from the all the tactics listed is substantial," the bulletin states. "If a suspicious item is reasonably believed to contain explosives, an IED, or other hazardous material, DO NOT touch, tamper with, or move the item. Only bomb disposal personal should handle any suspected devices that are located."

An internal FBI bulletin obtained by ABC News earlier this week stated that armed protests are being planned at all 50 state capitols as well as at the U.S. Capitol in Washington, least through Inauguration Day.

The warning comes after suspected pipe bombs were found last week outside both the Democratic National Committee and the Republican National Committee headquarters, just a few blocks from the Capitol where pro-Trump rioters stormed the building.

-ABC News' Aaron Katersky

Biden has chosen Dr. David Kessler, former commissioner of the Food and Drug Administration (FDA), to help lead the federal government's COVID-19 vaccine initiative.

Kessler, a pediatrician and lawyer who headed the FDA from 1999 to 1997 under the Bush and Clinton administrations, will replace Dr. Moncef Slaoui, who is the current chief science officer to Operation Warp Speed.

Biden also announced several other appointees who will join his incoming administration's COVID-19 response team.

"We are in a race against time, and we need a comprehensive strategy to quickly contain this virus," the president-elect said in a statement Thursday. "The individuals announced today will bolster the White House’s COVID-19 Response team and play important roles in carrying out our rescue plan and vaccination program. At a time when American families are facing numerous challenges I know these public servants will do all that is needed to build our nation back better."

With just five days until his inauguration, Biden announced Thursday his pick to head the Federal Emergency Management Agency (FEMA) along with several other key posts for his incoming administration.

Deanne Criswell is his nominee for FEMA administrator. Janet McCabe is his nominee for deputy administrator of the Environmental Protection Agency (EPA). Shalanda Young is his nominee for deputy director of the Office of Management and Budget. Jason Miller is his nominee for deputy director for management at the Office of Management and Budget. And David Cohen is his appointee for deputy director of the Central Intelligence Agency (CIA).

"These dedicated and distinguished leaders will bring the highest level of experience, integrity, and knowledge to bear on behalf of the American people," Biden said in a statement Thursday. "Each of them brings a deep respect for the civil servants who keep our republic running, as well as a keen understanding of how the government can and should work for all Americans. I am confident that they will hit the ground running on day one with determination and bold thinking to make a meaningful difference in people's lives."

Alex Padilla, California’s Secretary of State and the man who will fill Vice President-elect Kamala Harris’ seat in the Senate, told ABC News he’s prepared to balance both the impeachment trial and response to COVID-19 when he’s sworn in next week.

“We have to be able to walk and chew gum at the same time,” Padilla said. “It’s not either or, COVID-19 response is absolutely important. Holding President Trump accountable is extremely important. And doing our part, as the Biden-Harris administration settles, is also extremely important. So we're prepared to do what it takes.”

He said he doesn’t know how the Senate will vote, but believes a “rebalanced leadership” with Democrats in the White House, Senate and House, will give the party “tremendous opportunity” to achieve their goals.

When asked whether he believes last week’s riot at the Capitol would embolden further attacks, he said, “Frankly, when I saw the images last Wednesday, it only emboldened my resolve to want to get to work, and want to get to work quickly.”

-ABC News' Allie Yang

House Democrats have opened an investigation into what law enforcement and the intelligence community knew about threats to the Capitol ahead of the Jan. 6 siege.

The investigation from the House Intelligence, Oversight, Homeland Security and Judiciary committees will also examine whether anyone with security clearances -- current or former National Security, Defense, Justice or Homeland Security officials -- participated in the riot.

The investigation will also examine the federal law enforcement response in the aftermath of the attack.

"The Committees will conduct robust oversight to understand what warning signs may have been missed, determine whether there were systemic failures, and consider how to best address countering domestic violent extremism, including remedying any gaps in legislation or policy," committee members wrote in a letter to the FBI, DHS and Office of the Director of National Intelligence.

"This still-emerging story is one of astounding bravery by some U.S. Capitol Police and other officers; of staggering treachery by violent criminals; and of apparent and high-level failures -- in particular, with respect to intelligence and security preparedness," the letter later stated.

Democrats plan to request documents and briefings from administration officials as part of the investigation -- just one of several looking into the Capitol attack.

-ABC News' Benjamin Siegel