The Gun Violence Archive has counted more than 300 mass shootings through early July

NEW YORK (TIP): A gunman killed seven people and wounded dozens more during a Fourth of July celebration in Highland Park, Ill., on Monday, July 4. It was one of several shootings on the holiday around the United States, according to the Gun Violence Archive, a nonprofit research group that tracks gun violence using police reports, news coverage and other public sources. The group defines a mass shooting as one in which at least four people were killed or injured. The deadliest mass shooting in the country so far this year was the massacre in which 19 children and two teachers were killed at an elementary school in Uvalde, Texas, on May 24. It happened 10 days after 10 people were shot and killed in a supermarket in Buffalo. There is no consensus on what constitutes a mass shooting, complicating the efforts of government, nonprofits and news organizations to document the scope of the problem. Different groups define mass shootings differently, depending on circumstances including the number of victims, whether the victims are killed or wounded, and whether the shooting occurs in a public place.

The Gun Violence Archive has counted more than 300 mass shootings through early July. Of those shootings, 15 involved four or more fatalities, including the one in Highland Park on Monday, July 4. The group recorded 692 mass shootings last year, with 28 involving four or more fatalities.

Here is a partial list of mass shootings so far this year.

July 4: Highland Park, Ill.

Robert E. Crimo III, 21, was taken into custody several hours after the shooting in Highland Park, a suburb north of Chicago, and charged with seven counts of first-degree murder. Seven people were killed and dozens more, ranging in age between 8 and 85, were wounded.

More on the Highland Park Shooting

Seven people were killed and many more wounded in a mass shooting at the Fourth of July parade in Highland Park, a Chicago suburb. The Limits of Restrictions: The 21-year-old gunman was able to buy several weapons despite Illinois’s relatively strict state laws and alarming police encounters.

Highland Park: The small town was designed as a leafy retreat for people seeking safety and quiet. In planning the attack, the gunman exploited the intimate setting.

A Violent Weekend: The Chicago attack was the largest and highest-profile shooting, but far from the only one over the Fourth of July weekend. The police said the gunman had climbed onto a rooftop with a rifle and begun firing into a crowd gathered for a Fourth of July parade.

June 30: Newark

Nine people were shot and wounded in what the police said appeared to be an incident related to a stolen car. The youngest victim was 17 and the oldest was 68. All were treated at local hospitals.

June 20: Harlem

A 21-year-old college basketball player was killed and eight people were wounded in an early-morning shooting at a popular picnicking area. After surging during the pandemic, the rate of shootings in New York has begun to fall, although it is still above pre-pandemic levels.

June 4: Philadelphia

Three people were killed and 12 injured in a shooting in downtown Philadelphia, the police said. An officer fired at one of the gunmen, the police said, but it was unclear whether the gunman had been hit.

Another six people were killed and dozens were injured in several other shootings over the same weekend, including in Arizona, South Carolina, Tennessee and Virginia.

June 1: Tulsa, Okla.

Several people were shot and five were killed at a medical building next to Saint Francis Hospital in Tulsa, Okla., the Tulsa police said. The police said the gunman was believed to have killed himself.

May 24: Uvalde, Texas

A gunman killed 19 children and two teachers at Robb Elementary School in Uvalde, Texas, about 80 miles west of San Antonio.

Law enforcement officers fatally shot the gunman, identified as Salvador Ramos, 18, but not until well over an hour after he walked into the school, raising questions about whether lives could have been saved if they had acted sooner. The U.S. Justice Department has said that it would review the law enforcement response.

May 15: Laguna Woods, Calif.

A gunman killed one person and critically wounded four other members of the Irvine Taiwanese Presbyterian Church in Laguna Woods, Calif. The congregation, which holds services at the Geneva Presbyterian Church, overpowered the gunman and hogtied him, preventing further bloodshed, the authorities said. The suspect, David Chou, 68, is a Las Vegas man with a wife and child in Taiwan who had traveled to Orange County with a grievance against Taiwanese people, the authorities said. He was charged with murder and five counts of attempted murder in what the Orange County sheriff, Don Barnes, called a “politically motivated hate incident.”

May 14: Buffalo

A gunman armed with an assault-style weapon killed 10 people and wounded three others at a Tops supermarket in a predominantly Black section of Buffalo, the authorities said. The suspect, Payton S. Gendron, 18, is white, and the 10 people who died were all Black. Before the attack, Mr. Gendron had posted a nearly 200-page racist screed online. He has pleaded not guilty. He faces life in prison if convicted.

May 13: Milwaukee

At least 16 people were wounded by gunfire in a shooting in downtown Milwaukee, in a popular nightlife area block from the arena where an N.B.A. playoff game ended hours earlier, the authorities said.

April 12: Brooklyn

A gunman opened fire inside a crowded subway car during the morning rush, wounding 10 people, the worst attack on New York City’s subway system in decades. More than a dozen other people were also injured, with some choking on smoke from the two devices the police said the gunman detonated before he started shooting. No one was killed.

A suspect, Frank R. James, was arrested the next day and charged with carrying out a terrorist attack on a mass transit system. If convicted, he could face life in prison.

April 3: Sacramento

As revelers spilled out of nightclubs in a two-square-block area of downtown Sacramento, a barrage of gunfire killed six people and wounded 12, the authorities said. Days later, the Sacramento Police Department said “gang violence” was at the center of the shooting, which involved at least five gunmen.

March 19: Dumas, Ark.

Two people engaged in a gunfight and sprayed a crowd with gunfire, killing one bystander and injuring 27 other people, including six children, at a community event and car show in the small Arkansas farming community.

Jan. 23: Milwaukee

Law enforcement officers were called to a Milwaukee home for a welfare check and found six people who had been fatally shot. The victims — five men and one woman — had been shot, the police said, and evidence early in the investigation suggested that the killings had been targeted.