At the height of protests last year over police violence against Black people, Pennsylvania’s lieutenant governor, John Fetterman, called for police officers to be better trained to defuse incidents where those involved did not threaten public safety.

“We must fall on the side of de-escalation every time,” Mr. Fetterman wrote, citing his experiences as mayor of the town of Braddock, outside Pittsburgh.

But as Mr. Fetterman — one of Pennsylvania’s most prominent Democrats — enters the race for U.S. Senate this week, an incident from his past highlights his own judgment in the heat of one such moment.

In 2013, when he was mayor, Mr. Fetterman used his shotgun to stop an unarmed Black jogger and detain him, telling the police that he had heard shots fired near his home and spotted the man running, according to the police report. “Fetterman continued to yell and state that he knows this male was shooting,” the police report says.

An officer who patted down the man, Christopher Miyares, then 28, found no weapons. The officer noted that Mr. Miyares was wearing running clothes and headphones. Mr. Miyares was released.

On Tuesday, in response to questions from The Times, Mr. Fetterman’s campaign shared a new two-and-a-half minute video in which the candidate described the incident and defended himself — a sign that his campaign anticipated that the events from eight years ago would resurface with potential political fallout for his Senate bid.

In the video, Mr. Fetterman says that he was outside his home with his 4-year-old son when he heard “this crushing burst of gunfire,” and “I immediately made a series of split-second decisions.”

He said he saw someone “dressed entirely in black and a face mask” running in the direction of an elementary school. Noting that the date, in January 2013, was not long after the Sandy Hook school shooting, Mr. Fetterman said, “I made the decision to stop him from going any further until the first responders could arrive.”

According to accounts Mr. Fetterman gave in 2013 to local media, he chased the man in his pickup truck and used a 20-gauge shotgun he kept in the truck to hold him until the police appeared.

“I believe I did the right thing,” Mr. Fetterman told WTAE-TV at the time. “But I may have broken the law in the course of it. I’m certainly not above the law.”

Mr. Miyares told the TV station in 2013 that Mr. Fetterman had pointed the gun at his chest; the mayor denied doing so. Mr. Miyares said the incident unnerved him, and he maintained that what Mr. Fetterman took to be gunshots were bottle rockets set off by a group of kids. Mr. Fetterman said no traces of fireworks were found in the area.

No charges related to the incident were brought against Mr. Fetterman, who was in his second of four terms as mayor. A search of public court records did not find any complaint or action taken by Mr. Miyares following the incident. A spokesman for the Allegheny County Police Department said on Tuesday that Mr. Miyares never filed a complaint with the department.

Mr. Fetterman is the first declared candidate in what is expected to be one of the marquee Senate races nationwide next year, and he is running at a time when law enforcement violence against Black men, racial profiling and other policing abuses are urgent concerns among Democratic voters. Mr. Fetterman has highlighted his work developing a community policing plan for Braddock with buy-in from the town’s predominantly Black population, and firing police officers with a history of complaints.

Defined by his progressive politics as well as an imposing appearance — he is 6-foot-8, has a shaved head and favors work clothes over suits — Mr. Fetterman built a national profile during his 14 years as mayor of Braddock, a town of fewer than 3,000 in the shadow of closed steel factories and struggling with high poverty. The dates of nine murders in the town are tattooed on his right forearm, a symbol of his commitment to stopping street violence. His efforts to revive Braddock with arts programs and urban farms earned him widespread media coverage, and he was elected lieutenant governor in 2018.

Last month, Mr. Fetterman quickly raised $1.5 million after emailing supporters and telling his 400,000 Twitter followers that he was exploring a Senate race. In his campaign announcement video he pledged to unify voters with left-wing politics and those in left-behind communities who flocked to former President Donald J. Trump. He is expected to face challenges in the Democratic primary by two or more of the state’s centrist members of Congress, including Representatives Conor Lamb and Chrissy Houlahan.

Mr. Fetterman’s nascent Senate campaign on Tuesday first emailed The Times a five-page document with contemporary news accounts that sought to emphasize that Mr. Fetterman did not know Mr. Miyares’s race when he pursued him, and to place their encounter in the context of what the document called a spate of gang-related gun violence in Braddock. The campaign then sent the video and a statement by Mr. Fetterman; he declined a request to be interviewed.

In 2018, Mr. Miyares was charged with multiple felonies in a separate incident, including kidnapping for ransom, making terroristic threats and reckless endangerment, according to publicly available court records. He is currently incarcerated in state prison in Somerset County, Pa., and could not be reached for comment.

Mr. Fetterman’s run-in with Mr. Miyares surfaced briefly in 2016 during an earlier Senate bid by Mr. Fetterman, when he ran unsuccessfully in the Democratic primary. At the time, he told The Philly Voice that his pursuit and detainment of the runner had nothing to do with race.

“The runner could have been my mother for all I knew, thanks to what the jogger was wearing,” he said.

In his statement released along with the video, Mr. Fetterman said the incident with the jogger had been spread by political opponents since 2015 “and it’s never gone anywhere because people here know that I did the right thing for my community.”

Most recently, a Republican who ran unsuccessfully last year for a House seat from western Pennsylvania, Sean Parnell, tweeted about the incident in July 2020. Donald Trump Jr., the former president’s eldest son, retweeted Mr. Parnell.

“I’m not going to just sit here while a bunch of Republicans who have never given a damn about racial justice launch these bad-faith attacks from the safety of their gated communities,” Mr. Fetterman said in his statement. “They’ve never had stray bullets hit their home, or had a bullet whiz by so close that you can feel the air move. When I ran for mayor, I made a commitment to do whatever I could to confront this gun violence — and that’s exactly what I’ve done.”

He noted that he was re-elected in 2013 by voters in Braddock, which is 80 percent Black.

That year, Mr. Fetterman won 75 percent of the 247 votes cast in the Democratic primary, and he ran unopposed in the general election.

Susan Beachy and Sheelagh McNeil contributed research.