WILMINGTON, Ohio – After an hour-long standoff that closed a highway and disrupted rural life, law enforcement officers shot and killed a man they believe attempted to break into the FBI office in Cincinnati on Thursday.

Authorities in Ohio declined to confirm the man’s name or describe his motives. But two law enforcement officials familiar with the case said investigators were looking into whether the man, whom they identified as Ricky Shiffer, had ties to extremist groups, including one that participated to the January 6 attack on the Capitol.

The day after the FBI raided former President Donald J. Trump’s private residence in Florida, a person with an account bearing Mr. Shiffer’s name posted messages on Mr. Trump, Truth Social, advising “patriots” to go to Florida and kill federal agents. On Thursday, the same account also appeared to confess to an attack on the FBI

The attack in Ohio came three days after officers served a search warrant at Mar-a-Lago, Mr Trump’s beachfront home and club, and a day after the manager of the FBI told reporters online threats against federal law enforcement were “deplorable and dangerous.”

The man, who officials say was wearing a body armor, attempted to break into the visitor control center outside the FBI’s Cincinnati field office in the Kenwood suburb around 9 a.m. morning, said Todd Lindgren, a spokesman for the office. He said an alarm was raised and officers responded.

Credit…Jeffrey Dean/Reuters

After fleeing, the man headed north on Interstate 71, officials said, where he was spotted about 20 minutes later by a state trooper at a rest area. That trooper began a chase and came under fire, said Ohio State Highway Patrol Lt. Nathan Dennis.

The chase eventually left the freeway and meandered along rural roads before coming to a halt near an Interstate 71 overpass near the town of Wilmington. Lt. Dennis said shots were exchanged. He said officers tried to negotiate with the man and then tried to subdue him with less than lethal ammunition. These efforts failed. The man eventually raised a gun, Lt. Dennis said, and officers opened fire, fatally wounding him.

The attack came over the course of a week as many Republicans criticized the FBI for searching Mr Trump’s home, with some calling it a dangerous weaponization of the Justice Department. Some right-wing figures have also made broader calls for violence and civil war.

On Thursday night, FBI Director Christopher A. Wray defended the bureau and spoke out against attacks on law enforcement.

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

Federal investigators said they are looking into Mr. Shiffer’s social media accounts. On Tuesday, a Truth Social account by the name of @rickywshifferjr posted a message encouraging people to head to Florida, where, as he wrote, “Mar A Lago is.”

“I recommend going, and being in Florida, I don’t think the authorities are going to break it off,” the message read. “If they do, kill them.”

Credit…Megan Jelinger for The New York Times

Then Thursday morning, a message appeared: “If you haven’t heard from me, it’s true that I tried to attack the FBI”

The New York Times could not immediately confirm whether the account, or other social media accounts, belonged to Mr. Shiffer.

A Twitter account by the name of @RickyShiffer expressed his approval for the far-right group the Proud Boys. Law enforcement officials said they are investigating whether he appeared in a video posted to Facebook on January 5, 2021, showing him attending a pro-Trump rally at Black Lives Matter Plaza. in Washington on the eve of the storming of the Capitol.

In May, the Twitter account @RickyShiffer responded to a photo of rioters scaling the walls of the Capitol on January 6 with a message claiming he was present in the building and which appeared to blame people other than Mr. Trump’s supporters. for the attack.

“I was there,” the message read. “We saw your henchmen do this.”

Mr Shiffer has not been charged with any crime related to the January 6 attack. At an address in Columbus, Ohio believed to be linked to Mr. Shiffer, police cruisers were parked outside Thursday night and crime scene tape was blocking access.

In the rural area where the standoff took place, daily life was turned upside down on Thursday. For hours, residents of Clinton County, Ohio watched as police swarmed and helicopters hovered overhead. When Rob Thompson left to run errands shortly after 10 a.m., he was met at the end of his driveway by a high-speed white Ford Crown Victoria chased by several police officers.

“I thought, since we’re near the highway, they were just chasing a speeder,” said Mr. Thompson, who said his family has owned and farmed 4,000 acres near Wilmington, Ohio, for three generations.

Credit…Megan Jelinger for The New York Times

He soon learned that the man being pursued, who had stopped about half a mile from his driveway at the edge of a cornfield, was wanted for attempting to break into the FBI office. The tall corn blocked his view of the cul-de-sac, but Mr Thompson said he went to the top of his grain bins to get a better view.

At 73 Grill, near the site of the cul-de-sac, residents spoke of troubled days and difficult times. Edgar Castillo was preparing for the lunch rush at the grill on Thursday – double cheeseburgers are the big draw – when sirens disrupted the usually quiet community.

“I saw a lot of cars and police everywhere, and I didn’t know what was going on, but I had to pack lunches for the delivery,” Mr Castillo said.

Other residents were alerted to the unrest by the Clinton County Emergency Management Agency, which sent text messages telling them to shelter in place.

“My boss pulled out his gun, we got out and started watching the cornfields,” said Donna Bowman, who works on a nearby farm. “Because we were told the shooter was hiding in a cornfield, but we didn’t know where.”

Johnny Diaz, Amanda Holpuch and Lucie Walinchus contributed report. Kitty Bennett contributed to the research.