A line of black hearses left a Baptist church near here and crawled through the streets of St. Louis with lights flashing and horns honking. Only one thing was missing from the afternoon funeral procession: a corpse.

The motorcade last week was a protest of sorts, a message from morticians and funeral directors that business has been much too good.

“Many people would think I marvel on the number of homicides, like I’m a profiteer,” said Ronald L. Jones, a St. Louis funeral director. But “it disheartens me when I see young people walking through my funeral home and look at the display room and say, ‘This is the casket I want.’ It means they think they have nothing to look forward to but the grave.”

Even before a fresh wave of unrest engulfed suburban Ferguson this week, violence was on the rise in metropolitan St. Louis. Homicides have spiked by nearly 50 percent in the first half of this year, compared with 2014, and no one is quite sure why or what to do about it.

Some blame the “Ferguson effect,” the notion that police are avoiding aggressive tactics because they fear scrutiny or criminal charges in the wake of Michael Brown’s death by police gunfire one year ago. Others say the shooting of Brown, a black 18-year-old, by Darren Wilson, a white police officer, has undermined trust in police and, in turn, emboldened criminals.

But violent crime began creeping up in St. Louis months before Brown’s shooting, according to Richard Rosenfeld, a criminologist with the University of Missouri at St. Louis. And except for the first few months after Brown’s death, when violent protests were raging, he said, arrest rates have remained constant.

That’s left police and community leaders pondering more prosaic explanations: increased gang violence. Expanding drug markets. Too many guns with too few consequences or too few social programs.

“It’s alarming,” said St. Louis Mayor Francis G. Slay (D), “because it is difficult to ascribe a single concrete reason for it.”

St. Louis is not alone. After decades of falling crime rates, major metropolitan areas around the country are seeing an uptick in homicides and shootings. Baltimore, Chicago, Dallas and Milwaukee have reported similar increases. Among 35 cities recently surveyed by the Major Cities Chiefs Association, homicides were up an average of almost 20 percent.

“We have not seen what we are seeing right now in decades,” said D.C. Police Chief Cathy L. Lanier, who summoned big-city chiefs to a summit to discuss the problem last week. In the District, homicides have risen about 26 percent in the first half of this year.

Although the trend is alarming law enforcement leaders, criminologists are counseling patience. They insist that the surge in violence in some cities does not necessarily herald a new era of rising urban crime.

“I know there is a tendency to look at any type of crime increase and say the sky is falling,” said Eric Piza, a professor of criminology at the John Jay College of Criminal Justice in New York. “It’s going to take a little bit of time before we’re able to digest what is happening.”

Franklin E. Zimring, author of “The Great American Crime Decline” and director of criminal justice studies at the University of California at Berkeley School of Law, noted that killings are up slightly in New York, but the city is still on pace to end the year with one of its lowest homicide rates in modern history.

“Crime is low in most cities in the United States and at levels the public is quite comfortable with,” Zimring said.

Large swaths of the public are growing increasingly uncomfortable, however, in St. Louis, where 159 people were killed last year. That was an increase from 120 killings in 2013, and the pace of homicides has continued to climb in the first half of this year.

A protest from on high

Daniel “Boone” Fuller has noticed. The billboard company owner holds regular safety meetings with his employees, including a “murder report.”

Two women were recently shot under one of his billboards, Fuller said. At another location, Fuller reported he couldn’t do work on a billboard “until they washed the blood and brains in the gutter.” A man had been shot in the face outside a barbershop nearby.

Fuller found the increase in violence so disturbing that he mounted a demonstration this summer, vowing to live on one of his billboards until the city went seven days without a homicide. He slept in a hammock, took bucket showers in the heat and let grieving family members cry on his shoulder.

“My brother, he was number 62,” Fuller recalled one woman telling him.

“Boone, they killed my son, and there was 100 evidence markers,” another woman reported. “They shot at him 100 times with an AK-47.”

Fuller climbed up on his billboard July 9. He didn’t come down for 24 days.

Jones and his fellow funeral directors are equally distraught after seeing the pain of the bloodshed firsthand. Jones cringes at the thought of embalming another baby killed in a drive-by, another store clerk slain during a robbery or another young man riddled with bullet wounds from an AK-47.

“I’m very appalled by it,” he said.

The problem was on display in Ferguson on Sunday night, when peaceful protests to mark the anniversary of Brown’s death devolved as night fell into looting and gunfire. Though Ferguson is a separate city with a separate police force, the border is porous, and violence is a growing problem.

Three people were shot and wounded that night. Two were injured in a drive-by shooting in the neighborhood where Brown was gunned down. A third man, Tyrone Harris Jr., 18, was shot by police as he allegedly opened fire on an unmarked police car after a shootout between two rival groups fighting over a looted flat-screen TV.

On Tuesday, St. Louis County police released surveillance video showing Harris pulling out a handgun moments before the car came under fire. Harris, who remained in critical condition, has been charged with four counts of assault on law enforcement, five counts of armed criminal action and one count of discharging or shooting a firearm at a motor vehicle.

“It’s scary for the kids,” said Tony Reed, 21, who stood on Canfield Drive on Tuesday, yards from where both of the shootings occurred. “It’s going from blocking traffic to cussing to shooting and people getting hurt.”

‘No real pathways’ for youth

While much attention has been paid to police treatment of minorities since Brown’s death, many in Ferguson say the intense scrutiny has overshadowed a host of socio-economic ills that have long plagued the city. The high school dropout rate is high. Among those who graduate, few make it to college. Good-paying jobs are scarce.

“There are no real pathways for them to become productive members of society,” said Adolphus Pruitt, president of the St. Louis chapter of the NAACP. “They’re caught up in an environment in which our people are cannibalizing each other.”

James Clark works with Better Family Life, which urges an end to the violence. The organization’s yard signs — “Stop Killing Each Other,” they say — are sprinkled across St. Louis and Ferguson.

“What we are experiencing is a result of over two decades of neglect for the human capital in the urban core,” Clark said. “We are in a new era.”

Clark’s group urges people to call for help. But St. Louis Alderman Antonio French, who founded the nonprofit group Heal STL, said that isn’t happening as often as it used to. People who once could be counted on to combat neighborhood violence are now wary of police, and in some neighborhoods, relations with law enforcement have turned hostile.

“We’ve had incidents where police have shown up to a scene where a child, a toddler, was shot,” French said. “When they showed up to help the child, they were booed.

“This really just shows how vital it is to do this work to repair this relationship.”

Bui reported from Washington. Phillip and Lowery reported from Ferguson, Mo. Peter Hermann in Washington contributed to this report.