It’s been quite the baptism for John “Jack’’ Dempsey as head of the city’s fire department.

He assumed the mantle of Boston fire commissioner on an interim basis on the same day the president declared a national emergency, the Boston Marathon was postponed for the first time in its storied history, and the city’s school district, the largest in the state, was closed. All because of the COVID-19 pandemic.

By the time his interim title was removed last Friday, life in the city remained significantly altered by the coronavirus outbreak.

Perhaps unsurprisingly, when asked about the department’s biggest challenge, Dempsey named the most immediate one: the virus that has infected more than 9,000 city residents to date.

“To tell you the truth I was appointed right at the beginning of this and that has pretty much been the main focus," said Dempsey during a recent interview with the Globe.

To be sure, the department finds itself wrestling with other issues. Dempsey is inheriting an agency that continues to be faulted for its lack of diversity and a male-dominant culture. And there is festering discord between the department and the firefighters union, one of the city’s most powerful labor groups. A judge recently dismissed a lawsuit alleging the department had repeatedly violated its collective bargaining agreement, but the union has said it is taking the matter to arbitration.

When talking about the department’s diversity, Dempsey echoed his predecessor, saying “our hands are tied to some extent with civil service law but on the other end we have been actively recruiting’’ women and people of color.

“I think every department wants to reflect the population it services,’’ he said.

Last month, a department spokesman said civil service regulations like the preference for military veterans can limit a department’s ability to add more diversity to its ranks. At that time, city authorities said of the department’s 1,400-plus firefighters, 409 were people of color and only 17 were women. Black, Latinx, and Asian residents constitute a majority of Boston’s population.

But lately the focus is the pandemic. Like everything else, the public health crisis is an unavoidable fact of life for Dempsey’s department, which dates back to 1678. As of Tuesday, 26 firefighters remained out because of the coronavirus; 11 had confirmed cases. The outbreak has also slowed planned construction of a new firehouse in the city’s Egleston Square neighborhood.

Dempsey said the department at the start of the pandemic ceased day-to-day transfers between the stations that under normal circumstances occurred to make sure there is equal strength across the city. Now, the city’s 33 active firehouses effectively act as 33 silos, and the only time firefighters from different firehouses interact is when they are fighting a fire, he said.

“We’re still putting out fires, going to car accidents,’’ said Dempsey. “We’re doing everything that we normally do.’’

Dempsey said he is comfortable with the amount of personal protective equipment the department has and thinks morale is “relatively high right now’’ among the rank-and-file. The department has at least 56 pieces of firefighting apparatus — 33 engines, 20 ladder trucks, two rescue vehicles, and a marine vessel — and Dempsey is satisfied with the state of the department’s fleet.

A Hyde Park native who grew up the fourth of five children, Dempsey described his upbringing as working class. He enlisted in the Coast Guard before joining the department at age 28. Thirty four-plus years later, he now oversees a department that has a $271 million annual budget. His current post, which pays $250,000, is not one he pictured himself in five years ago, he said.

The most rewarding aspect of firefighting, he said, is helping people through moments of distress.

“It’s a great feeling."

The worst part?

“A child fatality is probably a firefighter’s worst moment,’’ he said. “Thinking, ‘That could be my kid.’ ’’

His previous department roles included acting as the city’s fire marshal, where he was in charge of enforcing the fire code amid Boston’s building boom and overseeing the department’s fire investigation unit. Before he was named interim commissioner last month, Dempsey, a 62-year-old married father of four, spent a short stint as the department’s chief of operations.

He succeeds Joseph Finn, who retired in March after serving for more than five years as commissioner. Dempsey said that he will look to build “on the solid foundation of his predecessors.’’

In the wake of Finn’s retirement announcement, some city councilors advocated for a leader who would make the city’s very white and very male department more diverse.

Additionally, in early 2019, a city-commissioned report found the department had a “male-dominant’’ culture resistant to change. Critics of the report said it recycled old recommendations and did not go far enough to address systemic issues.

Asked what could be done to change the department’s culture, Dempsey said, “There’s no silver bullet for fixing something like that.’’

“That’s going to take serious time, it’s not something we can fix in a month or in a class,’’ he said.

He added, “Everybody should respect everybody.’’

Advocates have said that a fire cadet program would help make the department’s ranks more diverse, but so far, such an initiative has yet to become a reality. Mayor Martin J. Walsh signed a home rule petition to start a fire cadet program last year. That kind of petition needs approval from the Legislature, which it has yet to receive.

Regarding such a program, Dempsey said, “I’m open to all options.’’

There is also the ongoing dispute between department management and Boston Fire Fighters Local 718. The union recently sued the department and Finn, citing three instances in which the department changed the status of firefighters from injured leave to either sick leave or light duty, which would force the firefighters to work or use up their sick time.

While a Suffolk Superior Court judge dismissed the complaint last month, Robert Petitti, president of Local 718, is hopeful his union will prevail at arbitration.

“The members are still being, in my opinion, mistreated,’’ said Petitti. “They are violating the contract.’’

However, Dempsey said he did not think the issue would be a bone of contention within the department, adding that Boston Fire treats its workers fairly and follows the collective bargaining agreement.

Despite his union’s current dispute with management, Petitti said Dempsey has a “great reputation as a fire chief.’’

“He has a good background with the administrative side of the job and I think he’s going to be a great pick,’’ he said.

Danny McDonald can be reached at daniel.mcdonald@globe.com. Follow him on Twitter @Danny__McDonald.