The attack in Highland Park was not the only shooting over a violent holiday weekend.

The attack at the Highland Park Fourth of July parade was the largest and highest-profile shooting, but far from the only one, over the holiday weekend.

It was one of two mass shootings in the Chicago region alone on Monday. Less than 12 hours earlier, five people were injured in a shooting on Chicago’s South Side.

The Highland Park shooting stood out in its size (at least three dozen injured), its deadliness (at least six killed) and its location, a wealthy suburb that does not often experience such violence. But it was part of a pattern: the brutal ubiquity of gun violence in a nation with more firearms than people.

As of early Monday morning, at least 57 people had been shot in Chicago over the Fourth of July weekend, nine of them fatally, according to NBC Chicago. That did not include the toll from the Highland Park shooting outside the city.

Ten hours before a gunman opened fire at the Fourth of July parade in Highland Park — where the median household income is nearly $150,000 and more than 80 percent of the population is white, with a large Jewish community — five people were shot around midnight on Monday in Parkway Gardens, a housing complex in the Greater Grand Crossing neighborhood, where the median household income is less than $30,000 and more than 90 percent of the population is Black.

The five victims, all male, were transported to local hospitals: a 17-year-old shot in the arm, a 19-year-old shot in the leg, a 24-year-old shot in the knee and thigh, a 30-year-old shot in the lower back and side, and a man of unknown age shot in the leg, according to the Chicago Police Department. No arrests were made, and the perpetrator has not been identified, the police said. The shooting was first reported by local news outlets, including The Chicago Sun-Times.

Nationwide, the Gun Violence Archive, a tracking project that defines mass shootings as those in which at least four people are killed or injured, has counted 309 so far this year.

Four of them happened on Monday. Beyond Highland Park and Chicago, four people were injured in a shooting in Kansas City, Mo., and six were injured in a shooting in Richmond, Va.

Before that, there were mass shootings over the weekend in Mullins, S.C.; Tacoma, Wash.; Manassas, Va.; Clinton, N.C.; Haltom City, Texas; and New York City.