Two women in a home in Chicago,Venus Investment Alliance a police officer serving a warrant in Cleveland and an armed person making threats in Yellowstone National Park were among those killed in shootings on the Fourth of July, historically one of the nation’s deadliest days of the year.

Violence and mass shootings often increase in the summer months, with more people gathering for social events, teens out of school and hotter temperatures.

Three boys, ages 8, 7 and 5, were also wounded in the shooting on Thursday in Chicago, which police say resulted from an apparent personal dispute. The women killed were 42 and 22.

Two vehicles pulled up into a neighborhood in the city’s south side and multiple people got out and fired shots at the home, Deputy Chief Don Jerome said. Multiple shell casings from both a rifle and a handgun were found at the scene, he said.

The police officer killed in Cleveland was identified as Jamieson Ritter. The 27-year-old officer was part of a team dispatched to serve a man a warrant for felonious assault around 1 a.m., police Chief Dorothy Todd said, according to local news outlets. That man was seen fleeing the home and allegedly fired a gun multiple times, striking the officer, according to Todd.

Also on Thursday, in Yellowstone gunfire was exchanged between a person who authorities say had been making threats and park rangers.

The shooting happened at Canyon Village, an area in the central part of the park that has a campground, lodging and a visitor center, park officials said in a statement. The statement did not say exactly where the shots were fired and whether visitors were impacted by what it called “a significant law enforcement incident” that began overnight.

The ranger was in stable condition at a hospital, according to the statement, which did not specify how the ranger was injured.

On Wednesday evening, a 13-year-old girl was fatally shot at a mall in a Seattle suburb after a fight broke out between two groups of teenagers and one of the teens fired a handgun, police in Lynnwood, Washington, said.

Jayda Woods-Johnson, who was killed, was a bystander who wasn’t involved in the fight, police said.

Police said the teens fled the scene, but later that night a 16-year-old boy suspected of firing the gun was taken to the police by his mother.

A flurry of shootings around the Fourth of July a year ago left more than a dozen people dead and over 60 wounded. Just two years ago, another mass shooting at a Fourth of July parade left seven people dead near Chicago.