Fatal opioid overdoses are on the rise again in the nation’s capital, an alarming development for public health officials who had celebrated what previously appeared to be a downward trend in the city’s drug deaths.

Preliminary data indicates that 220 people died of opioid overdoses in the District in the first 10 months of 2019. If that fatality rate holds for the final two months of the year — which are still being analyzed — the District will log more than 260 fatal opioid overdoses, a 24 percent increase over 2018. That would also make 2019 the second-deadliest year for drug users since the District’s opioid crisis began five years ago.

The increase comes despite efforts by the administration of Mayor Muriel E. Bowser (D) to step up the city’s response to fatal opioid overdoses, launched last year as part of a long-awaited strategic plan to fight the epidemic.

It also comes amid an unprecedented cascade of federal dollars into the District, which has been awarded more than $50 million over two years by the Trump administration for anti-opioid initiatives.

D.C. Council members said they were surprised and disheartened by the overdose data at a council health committee hearing Friday.

Health committee chairman Vincent C. Gray (D-Ward 7) called the statistics “deeply disturbing” and said they depict “a startling increase and trend moving in the wrong direction.” He said he was eager to hear how the Bowser administration planned to respond to the upswing in fatal overdoses.

“I need to hear creative solutions and a tremendous sense of urgency,” Gray said.

Nationally, the Centers for Disease Control and Prevention released data this week showing fatal drug overdoses declined in 2018 for the first time in 28 years. But the CDC has also released provisional data reflecting a slight national increase in deadly overdoses during the first six months of 2019.

In neighboring Maryland, statewide opioid-related deaths declined during the first nine months of 2019 compared to the same period the previous year. However, deaths increased in Baltimore, a city that — like the District — has been devastated by fentanyl.

The District was spared the worst of the early waves of America’s long-running opioid epidemic, when the abuse of prescription painkillers led to exploding overdose rates.

But beginning in 2015, the city was hit hard by the synthetic opioid fentanyl. Many longtime drug users, primarily older black men, began dying from heroin contaminated with fentanyl. The epidemic peaked in 2017, when the city saw 281 fatal overdoses.

The death toll dropped substantially in 2018, to 213 victims. But in 2019, it appears to have rebounded — and city officials are struggling to understand why.

Wayne Turnage, deputy mayor for health and human services, said the year-over-year rise seems to have been driven in part by more fatalities among younger drug users and non-District residents who overdose within the city.

He also noted that fentanyl is more widespread than ever, showing up in roughly 9 out of 10 overdose victims.

“We have a population that is using drugs that have a higher lethality, and that is impacting the younger age group in a way we didn’t anticipate,” Turnage said in an interview. He said that senior city officials have begun meeting “to figure out what can be done to target these new populations.”

Yet the number of District residents who fatally overdosed is also on track to rise and, even in older age groups, the figures are not encouraging. Deaths appear likely to remain essentially flat in 2019 among victims between the ages of 40 and 59, while the number of deaths among those aged 60 to 79 has already surpassed the 2018 total.

The rising deaths come amid growing recognition of and efforts to address the District’s opioid overdoses, which community advocates and treatment providers said were ignored for years at city hall.

Those efforts came after The Washington Post published several stories on the city’s opioid epidemic and the D.C. government’s faltering response.

D.C. officials dramatically increased their distribution of the lifesaving overdose antidote naloxone, a campaign Turnage says may have reversed as many as 1,100 overdoses in 2019. The city also expanded treatment programs for drug users, though the initiative has been met with mixed reviews.

Turnage said the increasing opioid fatalities do not mean those efforts have been in vain, but they do point to the tenacity of the opioid problem.

“Because these drugs are so highly addictive and so difficult to wean people off of, we’re sort of in this for the long haul,” he said. “We have to redouble our efforts.”