Updated

The FBI on Monday released new photos showing the suspect or suspects allegedly responsible for placing pipe bombs in Washington, D.C., last week around the same time rioters stormed the U.S. Capitol, interrupting the official certification of Electoral College votes by Congress.

There is a $50,000 award for any information that leads to the location, arrest and conviction of the person or persons responsible for the placement of suspected pipe bombs on Jan. 6 at the Republican and Democratic national committee offices in D.C. 

It’s not clear whether the images released depict one individual or more than one dressed in a similar fashion. 

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With more protests planned before President-elect Joe Biden’s inauguration on Jan. 20,  security experts and law enforcement officials are concerned about the potential for additional bomb threats or attacks on so-called soft targets in Washington, like museums and government buildings that don’t have full security infrastructure like the White House.

A photo released by the FBI last week showed an individual dressed in a gray sweatshirt with a hood over his or her head and a white mask hiding the person’s face. The individual also wore gloves, sneakers, dark pants and carried a dark-colored backpack.

Additional photos released Monday were zoomed in to show the details of the backpack and shoes.  

"If you recognize this backpack or these shoes, submit a tip at http://fbi.gov/USCapitol," FBI tweeted.

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As large crowds of supporters of President Trump stormed the U.S. Capitol on Wednesday, federal agents were working at the same time to detonate two pipe bombs found just blocks away at the offices of the Republican and Democratic national committees.

At approximately 1 p.m. on Jan. 6, multiple law enforcement agencies received reports of a suspected pipe bomb with wires at the headquarters of the Republican National Committee (RNC) located at 310 First St. Southeast in Washington, D.C., the FBI said in its press release. About 15 minutes later a second suspected pipe bomb with similar descriptors was reported at the headquarters of the Democratic National Committee (DNC) at 430 South Capitol St. Southeast #3.

An explosive device is shown outside of the Republican National Committee office, Wednesday, Jan. 6, 2021, in D.C. (AP Photo)

The two explosive devices were very similar, and both were about a foot long with end caps and wiring that appeared to be attached to a timer, law enforcement officials familiar with the matter told the Associated Press.

Investigators are still examining the devices and their components to determine the specific compounds inside the pipe bombs, but they both appeared to contain an unknown powder and some metal, the officials said.

The FBI is also seeking the public’s assistance in identifying individuals who made unlawful entry into the U.S. Capitol building and assaulted federal law enforcement personnel on Jan. 6. Focus on the insurrection shifted public attention away from the explosives threat. 

Separately, while responding to calls about suspicious packages Wednesday, U.S. Capitol Police officers also discovered a suspicious red pickup truck with Alabama license plates near the Capitol, noticing the handle of a firearm on the right passenger seat, officials said.

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Officers ran the truck’s plates and called in the bomb squad to investigate. When they searched the vehicle, they found an M4 carbine rifle, loaded magazines, and 11 Molotov cocktails made out of Mason jars and rags.

Prosecutors described the items as something like "homemade napalm bombs" and arrested the truck's owner, Lonnie Coffman of Falkville, Ala. But they said Coffman is not suspected of leaving the bombs at the Republican and Democratic national committees.

The Associated Press contributed to this report.