Christopher Hellenthal could have changed out of his Spider-Man costume before leaving work on Tuesday. It was high noon and over 100 degrees in his Arkansas town.

Instead, he kept the costume on, mask and all, for the short drive home from his job at a trampoline park in Jonesboro.

“It’s skintight, but it’s breathable,” he said in a phone interview.

As Mr. Hellenthal, 20, stopped his red truck at a multilane intersection, he saw a man in a wheelchair struggling to cross the street at a red light. Mr. Hellenthal put the truck in park and jumped out to push the wheelchair to the other side. Then he sprinted back and drove away when the light turned green.

The interaction lasted less than a minute, but a traffic camera caught it on video and the Jonesboro Police Department posted the footage on social media hours later.

“Some people say cops are heroes, but even we need a little helping hand,” the department said in an accompanying post. “Earlier today, a citizen needing a little assistance got it in the form of a true superhero.”

On the internet, residents of Jonesboro and beyond applauded Mr. Hellenthal’s actions and marveled at his speed. Some wondered if the incident was a deleted scene from “Spider-Man: Brand New Day,” a movie that arrives in theaters next week.

Others asked if the episode might have been staged to promote the film — a suggestion that Mr. Hellenthal denied in an interview on Thursday. Neither Marvel nor Sony Pictures, the film’s distributor, responded to requests for comment.

Mr. Hellenthal said he did not know the man he had assisted. “I told him, ‘Don’t worry, I’ve got you,’” he said. “It happened really fast. I just kind of skedaddled out of there because the light turned green.”

It wasn’t the first Spider-Man sighting in Jonesboro, a long way from the Marvel character’s home in New York City.

Mr. Hellenthal said he had worn the red-and-blue suit around town a few times after buying it for $200 this year from an online costume store. Once, he picked up pizza at Little Caesar’s, which was offering a special “webberoni” pie to promote the web-slinging superhero’s new movie.

“I’d call and say, ‘My name’s Peter, I need to order a webberoni,’ and I’d show up there in the costume,” Mr. Hellenthal said, referring to Spider-Man’s alter ego, Peter Parker.

Mr. Hellenthal said he had worked at Ultimate Air Trampoline Park in Jonesboro for three years, mostly during his summer breaks from college at Arkansas State University. On Tuesday, the park hosted a superhero-themed event for children.

“I wanted a suit that would look real to them,” Mr. Hellenthal said.

Much like Peter Parker, Mr. Hellenthal said, he had an interest in the sciences. The character developed spidey senses after being bitten by a radioactive spider in a laboratory; the Arkansas iteration has been working toward a bachelor’s degree in wildlife.

“He’s always been my favorite superhero,” Mr. Hellenthal said. “He’s got problems like regular people. He’s not rich, and he’s real humble, not like Tony Stark,” he added, referring to the billionaire businessman behind Iron Man.

When he was 8, Mr. Hellenthal said, he wore a Spider-Man costume when his parents brought him to a Comic Con convention in Chicago to meet Stan Lee, the character’s creator.

Mr. Hellenthal’s father, Chason Hellenthal, a beekeeper, said by phone that his youngest son had been doing good deeds his whole life.

“It just so happened this got caught on camera,” he said.