ST. LOUIS » Across from the Little Explorer’s Learning Center, diagonal to a crumbling house where heroin dealers and hangers-on often mill about, a garland of teddy bears adorns a telephone pole, a memorial to the latest victim to fall here at one of this city’s deadliest corners.

The victim was a 27-year-old man shot dead Dec. 23, one of the last casualties in a year of surging gun violence.

"It’s nothing to get a firearm," said Michael Shelton, who was badly wounded by gunfire eight years ago at this same corner, in the bleak Wells-Goodfellow neighborhood of northern St. Louis, and is now determined to stay out of trouble. "I don’t know anybody who doesn’t carry or have easy access to one."

Murder rates have fallen sharply in most of the country. But St. Louis is one of a few major cities, including Memphis, Tenn., and Washington, where the number of homicides jumped last year. It is also one of several cities, including Baltimore; Detroit; Gary, Ind.; and New Orleans, where violent crime, concentrated in low-income minority neighborhoods, has remained stubbornly high, though down from the crack-driven peaks of the early 1990s.

The start of the new year was equally violent.

On Jan. 15, shaken by six murders in five shootings overnight, the city’s mayor, Francis Slay, called for more police, more surveillance cameras, more certain penalties for carriers of illegal guns and stronger gun laws, declaring: "Crime is the absolute No. 1 priority in the city of St. Louis."

A seventh person was killed on the afternoon of the mayor’s news conference.

Why St. Louis suffered a major setback in a year in which many cities saw further progress is hotly debated. By all accounts, the proliferation of guns among young men here is beyond control, turning petty insults, neighborhood rivalries and drug disputes into lethal melees of attack and reprisal that can occur in waves. There was a 33 percent rise in homicides last year, to 159, compared with 120 in 2013 in this city of 318,000.

Jennifer M. Joyce, the city’s circuit attorney, or prosecutor, an elected position, complains that in St. Louis, the illegal possession of a gun is too often "a crime without a consequence," making it difficult to stop confrontation from turning lethal.

At the same time, deeper social roots of violence such as addiction and unemployment continue unchecked. And city officials also cite what they call a "Ferguson effect," an increase in crime last year as police officers were diverted to control protests after a white officer shot and killed Michael Brown, an unarmed black teenager in Ferguson, the nearby suburb, on Aug. 9.

The violence is not uniform. Nearly all the increase in murders in St. Louis last year occurred in eight neighborhoods, said Richard B. Rosenfeld, a criminologist at the University of Missouri-St. Louis.

The largest jump was in Wells-Goodfellow, a desolate zone where more than a third of the houses are abandoned, liquor stores and churches are sprinkled among boarded-up shops and older residents fear stepping outside at night. In this neighborhood of fewer than 6,000 residents, 14 people were murdered in 2014, up from seven in 2013, for a per-person homicide rate five times the city average.

The mayor and the police chief, Sam Dotson, ascribe much of the rise in crime to the extended confrontations that followed the shooting in Ferguson and the failure of the grand jury to indict the officer, Darren Wilson. Normal patrolling of neighborhoods was interrupted, officers became tired and frustrated, and there was an intangible emboldening of criminals, these officials say.

Further raising tensions, racial distrust in a city that is half African-American and deeply segregated has intensified since the Ferguson shooting and the protests that followed. In late January, a hearing to discuss proposals for a civilian review board turned into a shouting match when police officers rose in opposition.

City officials are calling for the hiring of 160 more officers, with a special effort to bring more minority officers onto a 1,255-member force that is 35 percent black. In 2012, with crime in apparent decline, the city let the police force shrink by 80 officers.

Now, an overstretched department is forced to pick one neighborhood at a time to flood with officers. Last month, Dotson even asked the state Highway Patrol if it could lend a dozen men to help watch downtown streets; the agency declined.

As he waits for the city to find money for new hires, Dotson has required the department’s 60 detectives to wear uniforms in public as a way to increase the visible police presence.

Criminologists and Joyce, the prosecutor, play down the effect of Ferguson on violent crime, noting that murders were rising well before August, though Rosenfeld said that burglaries did rise last fall.

But everyone — politicians to social workers — points to persistent causes including poverty, a youth culture that glorifies gun violence and what some say has been an unusually permissive legal response to guns.

"Ferguson didn’t help, but this homicide rate had been building," Joyce said.

She called for tougher responses to gun possession, which she described as an early warning sign of violence to come.

Missouri, with a strongly pro-gun population outside the big cities, has permissive laws including one that allows the carrying of a loaded gun in a car without a permit. When the police discover a gun in a car with several passengers, including some with felony records, but no one admits to owning the gun, criminal charges are often impossible, Rosenfeld said.

In addition, according to a 2014 study by Rosenfeld and his colleagues, a majority of those who are convicted of illegally possessing a gun but not caught using it in a crime receive probation rather than jail time. Gun laws and enforcement are stiffer in many other cities.

Besides focusing on guns, Joyce also hopes to duplicate a much-praised program of the Manhattan district attorney, which tracks the most violent individuals and tries to make sure that, when they are picked up even for minor violations, they receive special attention from prosecutors.

Police officials, Joyce and others plan to visit Kansas City next month to look at the city’s "focused deterrence" policing initiative, which some say has helped to drive down the murder rate there. That approach, used with promising results in several cities, aims to identify the individuals most responsible for violence and confront them, promising intense police scrutiny and tenacious prosecution if they continue.

Dotson said in an interview that he would gladly adopt measures that helped, but he also noted that in 2003, a year homicides dropped suddenly in St. Louis to 74, others looked to the city for ideas.

More precise police work is well and good, said James Clark, vice president for community outreach at Better Family Life, a nonprofit social service group based in Wells-Goodfellow, just two blocks from the notorious intersection of Arlington and Ridge streets where the last murder of 2014 took place.

"But we’ve got to stop expecting the police to solve the crime problem," said Clark, adding that only with a huge increase in social aid could a cultural collapse be prevented. "There is a void that the police can’t fill."

Clark, a respected presence on the streets, is trying to help rescue youths and families one at a time, sending workers out to knock on doors and link people up with social services, from drug treatment to anger management to prenatal care.

"Our neighborhoods are resource deserts," he said. "Every neighborhood needs a center with drug treatment, GED lessons, recreation for the kids."

In 2007, after Shelton was shot, his grandmother was washing her car in front of the house on Ridge Street where she and her husband raised him and nine other grandchildren after their drug-addicted mothers lost custody.

Approached by a Better Family Life canvasser, she asked for help for her son.

Shelton, 25, has joined a support group at the agency, avoided a criminal record and hopes, with Clark’s help, to become certified as a security guard.

"I just found out that my girlfriend is pregnant," he said. "I plan to marry her. I’m very excited."

© 2015 The New York Times Company