CHICAGO (AP) — One person was killed and 10 were injured in two shootings on Chicago’s South Side in the space of six hours on Tuesday, a spasm of gun violence on the hottest day of 2022 so far, serving as a warning that the city is entering the warmest and deadliest time of year.

No one had been arrested in the shootings as of Wednesday morning.

Police said the first shooting happened at about 4:30 p.m. Tuesday when some people climbed out of a stolen car and opened fire in the Back of the Yards neighborhood. Five teenagers were shot, including a 19-year-old who was struck in the head and pronounced dead at a hospital soon after. His name has not been released.

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Two of the five were critically injured. A 16-year-old boy was struck four times including once in the face, and an 18-year-old man was shot in the hip and knee. Police said both are expected to survive.

The gunmen sped off, crashed the car then fled on foot, leaving three guns behind, police said.

Chicago Police Superintendent David Brown said investigators believe the shooting was part of an ongoing battle between two rival gangs that flared up last month when the brother of one gang leader was shot to death, allegedly by a rival gang member.

Brown said officers who responded to that shooting were attacked by gang members as they tried to administer life-saving measures to the wounded. He said two known gang members were arrested and charged with assaulting the officers.

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At about 10:30 p.m. in Jackson Park, where the Obama Presidential Center is under construction, occupants of an SUV opened fire, striking four women and two men, before speeding off. They were taken to hospitals and two of the women were in serious condition, police said.

Brown said that shooting could be linked to a dispute between two groups over the disruption of a rapper’s performance that was livestreamed on Facebook.

About an hour later, a man and a woman were wounded in another shooting in Jackson Park, but police couldn’t say if the two park shootings were related.

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It has been a violent year in Chicago so far. As of May 8, the police department had reported 194 homicides. That total is down slightly from the same period in 2021, a year that ended with 797 homicides — more than any year in a quarter century.

Chicago was among several cities, including New York and Los Angeles, to record more homicides in 2021 than in 2020.

And in recent weeks, there has been a spate of mass shootings — defined by the Gun Violence Archive as shootings in which at least four people were shot — in big cities and smaller communities across the U.S.