Police investigate a shooting that occurred in Chicago's Little Italy neighborhood early Friday.
CNN  — 

Gun violence is down across America this year but it peaks every summer and Chicago’s Fourth of July weekend bore the data out, with 109 people shot, including 19 fatally, police said in a Monday news conference.

All of the victims were boys and men ranging in age from 16 to 36 years old, according to police records.

This year’s violent holiday weekend comes as the city and the nation have seen a drop in gun violence in recent years.

As of June 24, Chicago had seen 1,105 shooting incidents so far this year, a 6% reduction from the same time last year and a 12% reduction over the past two years. The city had seen 271 gun deaths as of June 24, a 12% reduction since the same time last year and 16% reduction of the past two years, according to data from the Chicago Police Department.

Last year over the long holiday weekend, 57 people were shot and eight were killed between Friday, June 30 at 6 p.m. and Tuesday, July 4 at 11:59 p.m., according to Chicago police.

July 4 is the peak day for mass shootings in the US, more than any other single calendar day over roughly a decade, a 2023 CNN analysis of the Gun Violence Archive’s mass shooting data since 2014?found. The day with the second most shootings was July 5.

Gun violence is a ‘societal issue’

In the United States, law enforcement statistics and independent researchers have continually pointed to summer months as a time of increased gun violence, with July 1-7 being an especially violent period each year for both mass shootings and individual incidents.

Heat, experts say, can elevate discomfort and aggression?– a potential catalyst for violence at a time?kids are out of school?and warmer weather drives?more people outdoors?in a country with?more guns than people.

“When we look at what happened this weekend, we always like to say that it’s a police issue,” Chicago Police Department Superintendent Larry Snelling said at the news conference. “This is a societal issue. The police cannot be in everybody’s backyard. They cannot be in everyone’s home. They cannot invade every single gathering where there’s a possibility that someone may show up with a gun.”

“Everyone needs to be involved in this, this cannot just be the police department alone,” he added.

On Friday, after dozens of people had already been shot in Chicago, Mayor Brandon Johnson released a statement addressing the violence.

“We are devastated by the recent violence that has left our city in a state of grief and we extend our heartfelt condolences to the families and communities impacted by these recent events,” Johnson said in the statement. “The City of Chicago is committed to ensuring the safety of all residents and visitors.”

The city had canceled time off for police officers to “maximize presence and ensure prompt incident response,” activated an emergency services assistance center to provide support to people in the community and would hold a community rally Friday afternoon to “promote bonding, support, and healing,” according to Johnson.

But the efforts did not end the shootings.

Snelling urged public cooperation and tips to lead detectives to suspects, especially those who “make the choice” to shoot women and children.

“Those people have to be taken off the street,” Snelling implored. “They have to be put away. If we’re not doing that, then we’re failing other families. We’re failing people in our city.”

One of those killed over the weekend was an 8-year-old-boy who was shot alongside two other boys, ages 5 and 8, according to the Chicago Police Department’s online records.

Several 15- to 16-year-olds were also among those shot over the weekend, police say.

In another instance, eight people between the ages of 18 and 74 suffered gunshot wounds and in a separate incident, seven people aged 15 to 40 years old were shot. The 40-year-old died, according to the police department.

Officers are training for the upcoming Democratic National Convention next month to be better prepared for potential protests or civil unrest, Snelling said.

“Along with that, we have been working on a neighborhood plan to make sure that we’re not pulling resources that are necessary to keep our neighborhoods safe to place down and around the footprint of the DNC,” he said.

“Generations of disinvestment and deep disenfranchisement” have led to the state of violence within the city, Johnson said during Monday’s news conference. He is pushing for more federal resources to increase intervention and prevention of gun violence, including “more boots on the ground” to help get illegal guns off the streets.

“We are going block to block, neighborhood by neighborhood, to make sure that the city is safe and ultimately stop this violence,” said Johnson. “These are not just numbers on pages. These are our fellow Chicagoans.”

This story has been updated with additional information.

CNN’s Cheri Mossburg, Whitney Wild and Brad Parks contributed to this report.