The mayor of Albany never expected to spend her days attending funerals and comforting the families of those killed and injured in a spate of alarming gun violence she finds hard to explain.

“It shocks the conscience,” said Kathy M. Sheehan (D). “The disregard we are seeing for human life. … It’s trauma on top of trauma for our city.”

Eight people have been fatally shot in New York’s capital city this year, including six in May. Recently, Destiny Greene, 15, was killed in a quiet neighborhood a block from the governor’s mansion after a group of men opened fire during what police later said had been a meetup over a Facebook Marketplace ad.

Albany’s violent crime spike isn’t an outlier. Last weekend, at least 12 mass shootings occurred across nine states, killing 11 people and injuring at least 70, according to a database compiled by the Gun Violence Archive, a nonprofit group that tracks such incidents.

The carnage included a shooting outside a nightclub in Minneapolis, which killed two and injured eight. Another two were killed and a dozen injured when shots were fired at a house party in Fairfield Township, N.J., and three were killed in a shooting outside a bar in Youngstown, Ohio.

And this weekend, two people were killed and more than 20 injured in the Miami area after men with assault rifles and handguns began “shooting indiscriminately into a crowd” at a concert early Sunday, police said.

As the nation marks Memorial Day, the unofficial beginning of summer, many officials are concerned that this is a preview of what they could face in cities nationwide in coming months, when the onset of warm weather almost always marks a rise in violent crime. Some worry that the violence could be especially pronounced this season as Americans emerge back into society after a year of coronavirus-related shutdowns and restrictions.

In Albany, Sheehan last week asked for help from state and federal officials to curb the violence. Gov. Andrew M. Cuomo (D) agreed to deploy the New York State Police to back up the city’s beleaguered police force, which has struggled to keep up with what Sheehan described as a “startling” increase in illegal guns flowing into the community.

Sheehan said she was particularly disturbed by the way incidents of random anger and conflict seem to be escalated by the increased presence of guns. “What we seem to be seeing is that solving disputes with guns is becoming normalized,” she said.

Bolstered by federal money from the American Rescue Plan Act, Albany has raced to invest in violence prevention efforts and to get community outreach programs that were shuttered during the pandemic up and running in time for summer. But Sheehan said she is concerned that it won’t be enough. “I’m really worried,” she said of the approaching summer months.

Scores of cities across the country have reported double-digit increases in shootings and homicides. In Columbus, Ohio, police have counted at least 80 homicides this year, more than double the same period last year. Bigger cities also continue to see increases. In Chicago, 195 people had been killed as of early May, the highest number in at least four years, according to police statistics. Nearly 1,300 people had been shot, according to a Chicago Tribune database that tracks such incidents.

In Atlanta, the homicide rate is up 50 percent over this time last year, and Mayor Keisha Lance Bottoms (D) said she and her police commanders have been struggling to come up with concise reasons as they brace for a potentially rough summer.

In past years, Atlanta leaders say, they could link much of the violence to specific group and gang rivalries or the drug trade. But Bottoms said much of the recent violence has appeared to be far more random and is being driven predominantly by intense passions between individuals who usually “know each other.”

Bottoms said the “common denominator” for the crime wave is stress from the pandemic and last year’s racial justice protests following the murder of George Floyd. But she said she is considering a range of possibilities for the violence, including long-lasting emotional and psychological issues found among so-called long-haul victims of covid-19, the disease caused by the coronavirus.

“You are having people emerging with depression, anxiety, and they lost loved ones and have been out of work,” Bottoms said. “This has created the most unfortunate convergence of factors, and I believe that is what we are seeing playing out on our streets.”

Last week, President Biden proposed allocating $2.1 billion to fund Justice Department efforts to address the nation’s “gun violence public health crisis.” That’s in addition to his proposal in March to spend $5 billion over eight years on community violence prevention efforts to try to prevent violent crime.

But Bottoms and other local officials nationwide have pressed the White House to do even more — including increasing funding for mental health, substance abuse and behavioral health programs. Some of the Atlanta region’s most horrific recent crimes, Bottoms noted, have occurred during incidents of possible road rage where assailants appear to suddenly snap and shoot at another motorist.

“I think part of what is going on is a frustration overall with society, and that seems to be spilling out on streets,” Bottoms said. “And in Atlanta, that is proving to be very deadly."

Adam Gelb, the president of the Council on Criminal Justice, said the nature of some of the latest homicides has been troublesome. “People getting in beefs, fighting over parking spaces, or engaged in road rage kinds of things,” he said. “And they are armed.”

That has led to major strain on elected officials, Gelb said, with the public increasingly believing that crime is “spinning out of control” even though violent crime rates in most cities remain far below what they were in the late 1980s and early 1990s during the height of the crack cocaine epidemic.

Still, cities across the country have pointed to alarming trends over the past year. In Wichita, the city reported 59 homicides in 2020 — about one every six days — the highest total since 1993. Police Chief Gordon Ramsay said the trend continued into 2021, fueled in part by an uptick in shootings and other violent crimes carried out by children as young as 13.

“It’s unlike anything I have ever seen,” Ramsay said, adding that he has conferred with other police chiefs nationwide facing similar issues.

Ramsay blamed continued fallout from the pandemic, which had shuttered many community programs for at-risk youths. But the chief also faulted state lawmakers who passed juvenile justice reforms in 2016 aimed at keeping kids out of jail but did not fully fund the alternate treatment programs to stop them from committing future offenses.

He said juvenile crime had further strained a department where officers have struggled to keep up with increased shootings and murders. The Wichita Police Department has long had one of the highest clearance rates in the country for solving crimes and arresting those responsible, but that hasn’t felt like much of an accomplishment lately.

“We are at like 80 or 90 percent clearance rate. ... It’s not like we are not apprehending people for these crimes,” Ramsay said. “But they keep happening, which tells me it’s not just about police or criminal justice. It’s a problem that we as a country have to come together and solve.”

Some experts have detected some promising signs in recent crime data. In New York City, more than 500 people have been shot this year — the highest number in a decade and up more than 50 percent over the same period in 2020. But Jeffrey Butts, director of the research and evaluation center at John Jay College of Criminal Justice, said that percentage was better than the 158 percent increase in shootings reported last fall in the city, suggesting that the surge in violence, while still up, may be declining.

Still, Butts said that the factors that drove last year’s violence are unlikely to subside anytime soon, even as cities and states slowly loosen pandemic restrictions. Neighborhoods hit hard by job losses and other economic disparities are still likely to struggle, and the sense of alienation and anger that has been behind some of the violence is unlikely to dissipate anytime soon.

“I worry about the generational effect,” Butts said, pointing to research about the lasting impact the crack epidemic had on residents of neighborhoods most affected by that era of violence.

“We have a generation of adolescents who have been living through this, and especially if they live in a neighborhood where there was a lot of gunfire, who knows the lasting effect,” Butts said, adding that the trauma of the past year could be felt for “some time to come.”

Timothy Bella contributed to this report.