WASHINGTON — A man who claimed to have a bomb with him in a pickup truck near the Library of Congress surrendered to authorities Thursday afternoon, ending an hours-long standoff in the heart of the nation’s capitol.

U.S. Capitol Police said in a Twitter message that they were checking a suspicious vehicle near the Library of Congress. The Cannon, Jefferson and Madison office buildings have been evacuated. Police said there is a possible explosive device in the pickup truck, though no explosives have been found at this point.

Congress is not in session this week.

U.S. Capitol Police Chief J. Thomas Manger said the incident started around 9:15 a.m. when the man drove a black pickup truck onto the sidewalk outside the Library of Congress at First Street and Independence Avenue SE.

He said the driver told an officer who responded to the call that “he had a bomb” and the officer said he saw what “appeared to be a detonator.” Manger said negotiators were “hard at work” talking to the man and that he was hoping to have “a peaceful resolution to this incident.”

Manger said they did not know the man’s motives at this time. He said they didn’t know “a whole lot” about the driver but said officials do have a “possible name and identity” for the man.

Two law enforcement officials familiar with the investigation identified the man as Floyd Ray Roseberry of North Carolina.

At one point, a man who appeared to be in a pickup truck was live-streaming outside the area, talking about a revolution, calling on “other patriots,” and trying to get President Joe Biden on the phone. The Facebook live videos of the man who apparently is in the standoff with Capitol Police show what looks to be a bomb in his lap. He is holding a large canister with a battery-powered device on top. He also claims to have ammonium nitrate in the toolbox of his truck. He said the device is sound-activated, and will only go off if the truck windows break by a bullet or other means.

He claimed other vehicles in the area were set to explode and was waiting for Biden’s call.

“If you blow my truck up, it’s on you, Joe, I’m ready to die for the cause,” the man said in the video that came from a profile named Ray Roseberry.

A law enforcement official said investigators are aware of the video, and so far, the man in it is believed to be the only suspect. Authorities are clearing a broad area, however, as the man claimed to have planted or be aware of multiple bombs. Another law enforcement official said while the man in the video is the only suspect so far, it was too early to definitively rule out his claims of having other explosives or working with others.

Facebook spokesman Andy Stone said they removed the Facebook profile and are investigating.

The man was communicating with investigators at least in part using some type of dry erase board, an official said.

The latest threat comes months after a pro-Trump mob stormed the Capitol on Jan. 6, forcing the evacuation of Congress and disrupting the confirmation of Biden’s electoral college victory. Then, in April, a Capitol police officer was killed when a man rammed a barricade outside the building.

On Thursday, about 50 employees of National Capital Bank, who had been evacuated from their building, gathered in Seward Square around 11:30 a.m. A man holding a laptop walked from group to group, releasing them to go home for the day.

Chris Reddick, 64, the bank’s vice president of residential lending, said he’d been on the phone with a customer when he got an alert to evacuate.

”I said I’d call him back,” said Reddick, of Mount Vernon. “They didn’t tell us why we had to leave.”

Reddick said it’s the third time he’s been evacuated from the building since Jan. 1. This time, he made it out within five minutes.

As he stood in the shade under a tree, wearing a green plaid face mask, traffic from multiple road closures sat snarled near him. His wife, who was watching events unfold from home, sent him another text to see whether he was okay.

”It’s upsetting, and it scares my wife,” Reddick said.

In an alert to those in the Cannon House Office Building, officials said they should stay calm and relocate to the Longworth House Office Building, using the complex’s tunnels.

Many of those who were evacuated from nearby offices on the Hill appeared calm and were seen carrying laptops and chargers as they left the area.

The Bureau of Alcohol, Tobacco, Firearms and Explosives, the FBI and D.C. police said they are assisting the Capitol Police with the incident.

Metro said its trains on the Orange, Blue and Silver lines are bypassing the Capitol South station, which is closed. Shuttle buses are being requested, and riders are expected to see delays on those three lines.

In his live stream, the man claimed that the bomb in his truck would be detonated by a loud sound, such as a bullet shattering the glass, and then destroy the surrounding two city blocks. He also said there were four other “patriots” in four other cars elsewhere in the District.

“You don’t want to do it, Joe,” he said. “There are five of us here ... The revolution is on, it’s here, it’s today.”

The bomb, he said, was built by someone with military experience who had lost two legs. He claimed to be apolitical, but he aired disgust with Democrats for the withdrawal from Afghanistan and suggested Biden was not democratically elected. He also urged for airstrikes on Afghanistan to push out the Taliban.

He said “this isn’t about politics” and that he doesn’t “care if Donald Trump becomes president again.” He said all the Democrats in the Senate “should step down because the people don’t want you there.”

“Democrats, you’re killing America,” he said at one point. “You’re making people want to leave America. This is supposed to be a place people want to come.”

He said he had a wife, whom he had told he was going fishing through Sunday, as well as two children and a grandchild. At one point, he showed piles of coins in the back of the truck and said he threw $3,000 in cash onto a sidewalk.

”I don’t want to die,” he said. “I’m not hurting anybody.” He continued, “America needs a voice. I’ll give it to them.”

”You pop these windows out and it’s over,” he said. “It’s going to be a chain reaction.”

In a Twitter message, the Capitol Police advised people to “stay away from the area.”

The House sergeant-at-arms sent an alert to Congressional staff telling them to avoid the area and said it was “likely be a prolonged law enforcement response.”

The library is at Independence Avenue and Second Street SE, near the Capitol and House office complex.

Near Folger Park, two police officers blocked Second Street SE with a motorcycle.

Nearby, Ed Bradley, 51, waited to see whether he’d be allowed back into the Library of Congress. He’d been conducting research when he got an evacuation order at 10:45 a.m.

Bradley left in a rush, leaving behind his house keys, laptop and the chicken sandwich he’d packed for lunch. He wasn’t told why he had to evacuate, though he did later read about an apparent bomb threat on Twitter.

”My keys are still in my locker,” he said. “So I can’t go home.”

At the nearby Supreme Court, employees got a notice to evacuate around 10 a.m., according to Patricia McCabe, a spokeswoman for the court.

The court has been closed to the public since March 2020 because of the pandemic. The court is in recess, and the justices are on their own schedules. McCabe said she did not have a number on how many people left the building because of the notification, but it was far under the court’s usual head count. Employees were waiting nearby.

Washington D.C. Mayor Muriel E. Bowser, D, said she had been briefed on the “evolving situation near the Library of Congress.”

Rep. Gwen Moore, D-Wis., said on Twitter that her staff in D.C. were safe at the Capitol complex.

For some staffers who experienced Jan. 6, the security alerts brought unwelcome flashbacks.

”It evokes a lot of anxiety,” said Jordan Wilson, the director of operations and emergency coordinator in Virginia Republican Rep. Rob Wittman’s office.

With each security alert, it’s Wilson’s job to make sure the staff is safe and accounted for, to lock the doors and identify the nearest evacuation route if that becomes necessary. And with each security alert it grows more emotionally draining, Wilson said.

”I’ve been on the Hill for six years last month, and I can’t tell you how many people have left in the last six, eight, nine months, in both parties, just because these things are hard to go through, and it does beg the question, is it worth it?” Wilson said.

His mom reached out to him while watching the situation unfold on the news, just as she did after Jan. 6.

”And again today she asked, why are you still working here?” he said. “That’s a hard question to answer.”

By now, though, he said he’s been through this so many times that he has “learned to fight through it and just keep the trains running.”

The Washington Post’s Robert Barnes, Peter Hermann, Lizzie Johnson, Rachel Weiner, Paul Kane, Marianna Sotomayor and Drew Harwell contributed to this report.