Members of the Chicago Police Department in March. (Nuccio DiNuzzo/Chicago Tribune via AP)

As a brutal year continues in Chicago, the city’s spiking homicide numbers have resulted in grim milestones and headlines. It took only until the end of Labor Day weekend for the city to have more homicides this year than it did in all of last year. There are only two American cities with bigger populations than Chicago — New York and Los Angeles — and even if you combine their homicide totals, the tally still lags behind the Windy City.

Recent days have seen a wave of bloodshed that gave the city still more tragedy and, with it, further reminders of how staggering the violence has been this year. Over the weekend, police say 18 people were killed, making it the deadliest weekend for Chicago this year (exceeding the 13 people killed over the long Labor Day weekend and the 13 killed during Father’s Day weekend in June).

Police statistics released Tuesday show that the weekend’s violence pushed the city’s homicide total north of 600 for the first time since 2003, a figure that comes with two full months left in the year. At its current pace, Chicago could have more than 730 homicides this year, possibly eclipsing the city’s highest death toll in nearly two decades.

The weekend’s toll included twin 17-year-old brothers fatally shot during a drive-by and an eighth-grader reportedly killed while helping his father move. Chicago had 78 homicides in October alone, police say, a number that most major cities nationwide did not reach through the entire first half of the year. (San Antonio — which has 1.4 million residents, a little less than half of Chicago’s population — had 70 homicides during the first six months of 2016.)

Chicago had more than 350 shootings in October, authorities said, and by month’s end, Chicago police said there have been about 3,000 shootings resulting in more than 3,600 shooting victims.

The uptick in bloodshed in Chicago has drawn national attention, as it is one of numerous big cities whose homicide totals have increased recently. Violent crime and murder increased last year, according to FBI data, remaining far below the levels in decades earlier but still drawing attention for the sudden spikes in a handful of places. (Overall, violent crime rates are far below what they once were and are nowhere near historic highs. In 1990, the country had about 23,000 homicides, compared with about 15,000 last year; during the same span, the U.S. population ballooned by 72 million people.)

This increase nationwide last year was driven by a handful of big cities such as Chicago, Baltimore and Washington, which had most of the uptick in homicides. More than two dozen police agencies have said that killings in their cities had increased by the middle of the year. Although Chicago has been among those with rising numbers — and accounts for a significant share of the increase in homicides in big cities this year — the opposite is true in Baltimore (which had 259 homicides through last week, down from 280 a year earlier) and Washington (which had 113 homicides as of Tuesday, down from 134 the same period the year before).

The number of homicides in some other big cities is still increasing, but some of these shifts are relatively modest, such as in Los Angeles (homicides were up slightly through late October, increasing to 241 from 238 at the same point last year) and Philadelphia (where there were 235 homicide victims through Sunday, up from 229 at same time last year).

In New York, police touted that city’s decreasing crime levels Tuesday, saying that shootings and homicides are both down through the end of October. James P. O’Neill, New York’s police commissioner, said in a statement, “It is gratifying to see the members of the NYPD reach new crime reduction milestones.”

Police officials in Chicago say the increase in violence in their city is largely occurring in a handful of areas along the city’s South and West sides, and they have repeatedly cited illegal guns as a sizable factor in the violence.

Chicago’s tough gun laws are routinely invoked by commentators and politicians discussing the city’s violence, a group that includes Republican presidential candidate Donald Trump, who most recently mentioned that during one of his debates with Hillary Clinton, his Democratic opponent.

Although the city has strict gun laws (albeit not as restrictive as Trump and others appear to think), these laws do not stop someone from bringing a gun into the city from a neighboring state. This appears to happen somewhat regularly, according to data from the Bureau of Alcohol, Tobacco, Firearms and Explosives. And in a survey of Cook County Jail inmates from the Chicago area, most said they got guns from people in their social networks rather than buying them at gun stores or stealing them.

Police are trying to combat violence in Chicago, even as the department is struggling to restore community trust and rolling out reforms amid an ongoing Justice Department investigation. Authorities say they are working to pull illegal guns from the street, describing it as a mammoth effort in the face of the surging violence. According to police officials, the department has recovered more than 7,000 guns through the end of October, which translates to roughly a gun an hour. Police have also called on lawmakers to give stricter sentences to people who commit gun crimes to keep them off the streets.

“We will not allow the level of violence we’ve seen in some parts of the city to continue and I have laid out a comprehensive plan to build stronger community partnerships, which is crucial to making our streets safer,” Eddie Johnson, the police superintendent, said in a statement.

The department has also announced plans to revamp its crime-fighting strategy and said it hopes to hire 970 new officers in a little more than two years.

Further reading:

America’s police chiefs have questions for the presidential candidates

Violent crime and murders both went up in 2015, FBI says

Chicago’s staggering rise in gun violence and killings

What we know about the uptick in homicides in big cities across the country