CNN  — 

An armed man suspected of trying to breach the FBI’s Cincinnati field office Thursday was killed in Ohio after a vehicle chase and hours-long standoff with law enforcement, authorities say.

The suspect was believed to be armed with an AR-15 rifle and a nail gun, a federal law enforcement source told CNN, and was wearing body armor, according to officials in an Ohio county.

He was Ricky W. Shiffer, 42, of Columbus, the state highway patrol said Friday.

Authorities have not announced a motive. But Shiffer had been known to the FBI because he had an unspecified connection to the January 6, 2021, riot at the US Capitol, and because he had associates within a far-right extremist group, two law enforcement sources told CNN Friday.

A social media account bearing Shiffer’s name appears to have referenced an attempt to storm an FBI office that day. It also made a “call to arms” – and called for violence against the agency – after the FBI executed a search warrant Monday at former President Donald Trump’s Florida home. Authorities have not confirmed the account belongs to the suspect.

Here’s what we know about the attempted breach and the suspect:

What happened when the suspect tried to enter the office

At about 9:15 a.m. ET Thursday, an armed man tried to breach the visitor screening facility at the FBI field office, the agency said.

“Upon the activation of an alarm and a response by armed FBI special agents, the subject fled northbound onto Interstate 71,” FBI Cincinnati said in a statement.

Ohio State Highway Patrol troopers responded and found the suspect at an interstate rest stop in a Ford Crown Victoria at around 9:37 a.m., the patrol said.

The troopers tried to initiate a traffic stop on the suspect, but he fled and a vehicle pursuit ensued, highway patrol spokesman Lt. Nathan Dennis said. Shots were fired from the suspect’s car during the chase, he said.

The suspect exited the highway at state Route 73 in Ohio’s Clinton County – roughly a 45-mile drive northeast of downtown Cincinnati – and came to a stop on a road nearby around 9:53 a.m., the highway patrol said.

How the standoff unfolded

After stopping, the man got out and “engaged officers,” the highway patrol said. Gunfire was exchanged between law enforcement and the suspect, who used his vehicle for cover, they said.

The suspect was wearing body armor, according to the Clinton County Emergency Management Agency. A lockdown was in effect within a 1-mile radius of the standoff location, the agency said.

The standoff stretched for several hours as law enforcement tried to negotiate with the suspect, the highway patrol said.

“Once negotiations failed, officers attempted to take the suspect into custody by utilizing less lethal tactics,” the agency said. “At approximately 3:42 p.m., the suspect raised a firearm and shots were fired by law enforcement officers.”

The suspect was shot and died from his wounds on the scene, the agency said.

The FBI is investigating the circumstances that led to the suspect being shot, the bureau said.

It is unclear what less lethal tactics authorities used as they tried arrest him.

What we know about the suspect

The FBI is investigating Shiffer’s social media presence and whether he had ties to right-wing extremism, a federal law enforcement source told CNN.

On the social media platform founded by Trump – Truth Social – an account bearing Shiffer’s name made a post Thursday morning that appeared to reference an attempt to storm an FBI office.

The post was made minutes after the Ohio State Highway Patrol said the incident at the office in Cincinnati began, shortly after 9:15 a.m.

“Well, I thought I had a way through bullet proof glass, and I didn’t,” the user posted at 9:29 a.m. Thursday. “If you don’t hear from me, it is true I tried attacking the F.B.I., and it’ll mean either I was taken off the internet, the F.B.I. got me, or they sent the regular cops while.”

It’s unclear whether the user intended to write more, as the post stops after, “while.”

The FBI declined to comment on the account and its postings, citing an ongoing investigation. An image on the account matched a government ID photo of Shiffer, a law enforcement source told CNN

On the account, which has been active only the last few weeks, the user communicated to others with increasingly politically violent and revolution-minded thoughts.

But it was not until the FBI executed a search warrant Monday on Trump’s Mar-a-Lago home that the user began to fixate on responding with violence toward the agency.

“People, this is it,” the user wrote on Monday. “I hope a call to arms comes from someone better qualified, but if not, this is your call to arms from me.”

In that post, the user encouraged people to go to gun and pawn shops to “get whatever you need to be ready for combat.”

When another person responded to the user saying they would be sending his photo and information to the FBI, the Shiffer account user responded by saying, “Bring them on.”

It’s unclear whether the information was forwarded to the FBI.

On Tuesday, the user wrote people were heading to gather in Palm Beach, Florida – where Mar-a-Lago is located – and said if the FBI broke up the group, “kill them.”

The account’s user also claimed he was in Washington, DC, on January 6, 2021, but did not say whether he entered the Capitol. The poster frequently referenced a belief the 2020 election was stolen from Trump.

The FBI was aware of Shiffer himself due to a connection to the January 2021 riot, and because he had associates within the Proud Boys, two law enforcement sources told CNN on Friday. The Proud Boys are a far-right extremist group whose head, along with other group leaders, were charged with seditious conspiracy in the 2021 attack.

What role Shiffer may have played in the January 2021 riot is under investigation, the two sources said. The deadly incident unfolded as Congress met to certify Joe Biden’s 2020 presidential election victory.

Shiffer served in the US Navy from 1998 until June 2003, his releasable military records show. Aboard a US Navy submarine, he was a fire control technician, responsible for weapons systems.

How the FBI has responded

FBI headquarters is investigating the “agent-involved shooting,” the agency said. The agency has deployed a Shooting Incident Review Team to the scene, which is standard practice when an FBI special agent or task force officer discharges a weapon, a law enforcement source told CNN.

The review team will gather evidence, interview witnesses and ultimately determine whether the use of deadly force was justified, the source said.

“The FBI takes all shooting incidents involving our agents or task force members seriously,” a bureau statement reads. “The review process is thorough and objective, and is conducted as expeditiously as possible under the circumstances.”

FBI Director Christopher Wray released a statement Thursday evening condemning attacks on law enforcement and the FBI.

“Unfounded attacks on the integrity of the FBI erode respect for the rule of law and are a grave disservice to the men and women who sacrifice so much to protect others. Violence and threats against law enforcement, including the FBI, are dangerous and should be deeply concerning to all Americans,” Wray said.

A law enforcement source said Friday that the FBI is investigating an unprecedented number of threats against bureau personnel and property in the wake of the search of Mar-a-Lago – including against agents listed in the court documents.

The unsealed versions of the court documents redacted the agents’ names but a version of the search warrant that was leaked to the media didn’t black them out. The names of the two agents who signed the warrant paperwork are now circulating online.

CNN’s Evan Perez, Jessica Schneider, Donie O’Sullivan, Jason Hanna, Michelle Watson, Caroll Alvarado, Chuck Johnston and Dakin Andone contributed to this report.