IN BALTIMORE, 2017 started with 26 murders in 25 days. Then it got worse. Charm City is suffering through its bloodiest year in decades, a daily drumbeat of carnage impervious to community outrage and surge police deployments. Maryland’s biggest city is now on pace to exceed 400 killings this year — in per capita terms, worse even than Chicago, which is undergoing its own season of senseless slaughter.

Baltimore is a melting pot of dysfunctions, but that doesn’t easily explain the current bloodbath; after all, it was no less troubled from 2008 to 2014, when annual murders never exceeded 250. So many factors have combined to produce the homicide spree that began in 2015 — the same year riots erupted after Freddie Gray received fatal injures in police custody — that local officials often seem flummoxed in their attempts to unpack the causes.

Without doubt, they involve a police department that is understaffed, under-resourced and undertrained, and whose relations with the community it serves are strained to the breaking point. At least half of each year’s homicide cases are not solved, so killers can assume impunity. Disturbingly, the number of arrests has dipped even as murders have skyrocketed, suggesting that the police have continued to retreat, as they did after the riots following Mr. Gray’s death two years ago. The department’s reputation was further diminished when, just this week, prosecutors were forced to dismiss dozens of cases that relied on testimony from an officer who, in a video, appeared to plant evidence at a crime scene as two fellow officers looked on.

The force’s extravagant deficiencies, including pervasive racism, were laid bare in a Justice Department report last year, which led to an ambitious program of court-ordered reforms. Unhelpfully, Attorney General Jeff Sessions tried to derail the reforms; Baltimore’s own leaders and police insisted on moving forward with them.

The reforms, along with a concerted effort to improve staffing, recruitment and training, offer some optimism for the long term. In the short term, the outlook is grim. The rioters in 2015 targeted, among other businesses, pharmacies, whose copious supply of opiates flooded the market, fueling competition among vicious gangs that vie for control of the business and have no compunction about settling turf wars with bullets.

The gunplay takes place in neighborhoods with notoriously bad schools and few opportunities for advancement or escape. The city’s manufacturing base has been decimated in recent decades, and the near-quarter of the population that lives in poverty can gaze upon affluence and ease in upscale neighborhoods nearby.

The good news is that many residents, far from being resigned, are outraged. In May, an organization called Mothers of Murdered Sons called for a cease-fire over Mother’s Day weekend. It didn’t work — several people were shot, and at least two died, including a 17-year-old girl. Undaunted, a broad coalition of churches and grass-roots groups, mainly in the black community, has launched an energetic campaign for a 72-hour cease-fire for this weekend. T-shirts, fliers, a website and Facebook page are all promoting a peace rally this Friday night, with the slogan “Nobody kill anybody.” That, at least, is a start.