Sanjay Gupta, CNN’s chief medical correspondent since 2001 and a neurosurgeon at Grady Memorial Hospital in Atlanta, has earned the nation’s trust by explaining everything from battlefield medicine in Iraq, where he stopped to perform emergency surgery on a wounded Marine, to obesity and heart disease.

In recent weeks, Gupta has been working nearly round-the-clock, explaining the coronavirus outbreak and demystifying concepts such as pandemic and social distancing to an anxious American public. Even while sounding the earliest and loudest alarms, he has never seemed to get angry or pass judgment.

On Tuesday night, he did both.

The occasion was a segment with anchor Jake Tapper in which live footage was aired of people strolling, jogging, cycling and rollerblading along the Embarcadero, a picturesque waterfront stretch in San Francisco — normally an innocuous, pleasant scene. On most evenings it would also be a lot more crowded.

But coming in the middle of a pandemic in a city under a shelter-in-place mandate, the sight of a steady stream of people casually mixing and holding hands set off both Gupta and Tapper.

They stewed about it for nearly 20 minutes.

“How I behave affects your health. How you behave affects my health,” Gupta said during the segment. “Never, I think, have we been so dependent on each other, at least not in my lifetime, and we should rise to that occasion."

He later urged people to take action immediately.

“Most people aren’t going to get that sick with it, but a lot of people are going to get sick and some are going to die,” Gupta said, punctuating his remarks with pointed hand gestures. “What happens to them, how many people get sick and how many people die, is very much dependent on what we do right now. Not even tomorrow, certainly not next week, right now.”

Tapper was the first to react to the images from San Francisco, visibly unsettled by the waterfront’s level of activity. Meanwhile, Gupta chuckled wryly and shook his head in apparent disbelief.

“First of all, we see a whole bunch of people here who are not distancing,” Tapper said. “They’re holding hands and walking down the street. Normally I’d say bravo, but this is actually kind of enraging.

“Many people in San Francisco have clearly not gotten the message,” he continued.

Gupta nodded in agreement, telling viewers that the virus, which has infected more than 200,000 people worldwide and caused at least 7,900 deaths, is spreading across the United States — and will continue to do so unless more Americans start committing to taking preventive action. As of early Wednesday, more than 6,300 cases of coronavirus were confirmed in the United States, with 108 reported deaths.

Although Gupta repeatedly praised the White House’s change in tone toward the pandemic, the doctor said official statements and guidance aren’t translating into necessary action.

“I’m not someone who likes to be hyperbolic or shout these things from the roof, it’s just not my nature, but we know what needs to be done,” Gupta said, his brow furrowing. “The government knows what needs to be done. Public health officials know what needs to be done. It’s not happening right now.”

As the segment continued with Tapper calling attention to several states that held Democratic presidential primaries Tuesday and carefree spring breakers congregating on Florida’s beaches like “they’re making a teenage movie from the ’80s down there,” Gupta’s warnings to the public only intensified.

Waiting to do something isn’t an option, he said, stressing that it is still within people’s control to “alter the fate of what’s happening here.”

Tapper remained enraged into the next segment with CNN’s Dana Bash, calling what he was seeing “maddening.”

“My dad is turning 80 this month, you know?” Tapper said. “People out there who are millennials or younger and thinking, ‘Well, if you’re 80 years old, it only affects people who are in their 70s and 80s,’ which isn’t true, although obviously the people in their 60s, 70s and 80s are most vulnerable to it. What are you saying? That my 80-year-old dad, therefore, is fair game?

“Who the hell are you to be walking around just giving this to old people and you just flippantly dismiss it?” the anchor later asked.

Tapper’s reactions can be emotional. Gupta’s are not, at least in public, and his open frustration took some by surprise.

“I’ve never seen @drsanjaygupta like this,” Bash tweeted. “He is visibly frustrated that people aren’t listening.”

CNN political commentator S.E. Cupp cited Gupta’s comments in her own warning.

“If this doesn’t tell you how serious and real this is, I don’t know what will,” she tweeted. “Even if you are not sick, BE A GOOD CITIZEN and protect the rest of us, our kids, our parents, our healthcare workers.”

Still, some viewers did not see the problem in the scene.

As Gupta and Tapper noted on CNN, the “shelter in place” order does not bar people from leaving their homes to go for a walk, exercise, shop for groceries or visit a pharmacy. Many people pointed out that the Embarcadero was not nearly as crowded as it would be on a typical day. Others guessed that many of the out-and-about people were probably tourists. Some described Tuesday’s San Francisco as a “ghost town.”

“Instead of insulting SF for taking walks/runs outside, maybe read the shelter in place order, ask our mayor or the public health department, all of whom explicitly said these are OK,” one city resident said on Twitter.

But the scene of people venturing out despite the citywide order to stay inside may have tapped into a deeper frustration about large swaths of people ignoring public health advice in recent days.

As spring break began for many college students this week, Florida beaches filled with sunbathers. Party people have flocked to bars and nightclubs despite local orders barring large crowds. Several politicians have bucked public health experts by encouraging people to visit restaurants and bars if they feel healthy.

All of that physical contact defies President Trump’s recommendation to avoid gatherings of more than 10 people and the Centers for Disease Control and Prevention’s advisory to practice “social distancing” for the next eight weeks.

Watching seemingly healthy people put vulnerable populations at risk by ignoring medical professionals has been a source of exasperation for many, including Gupta.

“You’ve got to act as if you might be carrying the virus,” said Gupta, adding that he canceled his youngest daughter’s birthday party and a trip to visit his parents to avoid spreading the coronavirus.

For years, Gupta has played a dual role as journalist and doctor. In 2010, when he visited Haiti after an earthquake killed more than 100,000 and injured many more, Gupta treated a newborn baby while covering the medical response to the natural disaster. He said that in that moment he considered himself a doctor first, and a journalist second.

“If people need my help,” he told the Baltimore Sun in 2010, “if they ask me, then I’m certainly going to help them.”

Gupta slipped again into his role as a doctor on Tuesday, albeit this time as the nation’s doctor, when he pleaded with viewers to stop socializing to prevent the spread of coronavirus.

His celebrity as CNN’s chief medical correspondent amplifies his advice. Indeed, his reach as a commentator on the current pandemic is perhaps on a par with Anthony S. Fauci, the director of the National Institute of Allergy and Infectious Diseases who also serves on Trump’s coronavirus task force and appears on television regularly.

On Friday’s episode of “The Late Show With Stephen Colbert,” Gupta was one of the host’s final interviews before the show went on hiatus because of coronavirus concerns. He offered solemn advice to the late-night audience.

“I don’t think it ever should cross over into panic, because panic doesn’t serve any purposes,” he said Friday. “The idea that people should be concerned enough to really start to do things with their own lives that can help protect them, I think is real.”