St. Louis, Baltimore, and Detroit recorded the highest per capita homicide rates of major American cities last year. Six months into 2017, it looks likely that they will maintain the dubious distinction. Baltimore is on track to have the highest number of homicides per capita in the city’s history. St. Louis faces its highest rates since the crack wars of the 1990s.

Most of this year’s homicides in the top three cities were committed with firearms, according to data obtained from the cities’ police departments. In St. Louis, 96 percent of the 94 homicides recorded in the first half of the year were committed with guns. The same was true in 88 percent of Baltimore’s 170 homicides, and 81 percent of Detroit’s 136 homicides. The composition of gun homicides was essentially unchanged from the same period last year.

St. Louis recorded 90 gun homicides between January and June of this year; for Detroit, the total reached 110. The numbers are roughly equal to last year’s tallies, and put the cities on pace to match heightened rates of gun murders. Violence has spiked dramatically in Baltimore, where police recorded 149 gun homicides in the first half of the year — 26 more victims than during the same period in 2016.

Victims in Baltimore this year include a 19-year-old senior at the Excel Academy, shot in the face while trying to hail a cab — the school’s fifth slain student in 12 months. In April, a 28-year-old pregnant woman was fatally shot by her husband. In June, a 37-year-old mother was gunned down after she told police her son was being bullied. And then, earlier this month, came the murder of a 24-year-old brother of the police department’s spokesman, who took to Facebook to air his grief:

Desperate residents and community activists have launched a campaign for a 72-hour ceasefire on the first weekend of August. Their message: “Nobody kill anybody.”

Crime patterns dim the hopes for a reprieve. Monthly gun homicide numbers usually increase in the second half of the year, police data show.

Crime in the United States, including murder, has fallen dramatically nationwide since the 1990s. But in individual cities, and especially individual neighborhoods, the picture looks different. According to an April 2017 report by The Brennan Center, the left-leaning think tank, the 2016 murder rate for the 30 largest American cities increased by 14 percent from 2015.

Escalating levels of gun violence in some cities suggest that the national homicide rate — as well as the often overlooked rates for nonfatal shootings — may show a third consecutive bump when the final numbers are in for 2017. A Washington Post analysis of data collected by Gun Violence Archive, a nonprofit organization that tallies shootings through news articles and police reports, found that, in the first 200 days of the year, gun deaths have surged by 12 percent.