CHICAGO (CBS) — Two men were killed and at least 12 people, including three teenagers, were wounded in separate shootings since Friday evening.

The first fatality happened Friday about 6:09 p.m. in the Jeffery Manor neighborhood on the South Side, where Parrish Flournoy, 23, was shot multiple times during an argument over a bicycle, authorities said.

Flournoy was riding a bicycle in the 2100 block of East 95th Street when a man approached him and took the bicycle, police said.

Flournoy chased after the man as he rode off, police said, and the man began firing shots at Flournoy, who was hit in the arm, back and buttocks.

Paramedics took Flournoy, of the 7200 block of South Champlain Avenue, to Advocate Christ Medical Center in Oak Lawn, where he was pronounced dead at 9:08 p.m., according to the Cook County Medical Examiner’s office.

About 12:53 p.m. on Saturday, Hector Cruz, 27, was shot multiple times at Davis Square Park in the Back of the Yards neighborhood, authorities said.

Cruz and two teenage boys were at the park located in the 4300 block of South Marshfield Avenue when a man approached and shouted “Saints killer” before he opened fire, according to police and witnesses.

Cruz, of the 1700 block of West 43rd Street, was shot multiple times and taken to John H. Stroger Jr. Hospital of Cook County, where he died at 2:05 p.m., authorities said.

A 14-year-old boy suffered a gunshot wound to the stomach, police said, and paramedics took him to Comer Children’s Hospital at the University of Chicago Medical Centers.

A 15-year-old boy was shot in the elbow and taken to Mercy Hospital and Medical Center, police said. Both boys were initially listed in “stable” condition.

Among the 12 people wounded in separate shootings this weekend was a 13-year-old girl. Police said she was one of five people who were shot within an hour on the Far South Side.

The girl and a 44-year-old woman were shot about 3:21 p.m. while they sat inside a car at a gas station located near 99th Street and Vincennes Avenue, police said.

A uniformed police officer witnessed the shooting and chased the shooters to the 9800 block of South Throop Street, police said. A shootout erupted between the men and the officer, police said, but no one was injured.

Police were able to arrest one of the suspects, said police News Affairs Officer Daniel O’Brien, adding that charges were pending Sunday night. Police continued searching for the two other suspects.

About an hour after the two females were shot, three men were wounded—one critically—in the nearby Roseland neighborhood.

The shooting happened about 4:31 p.m. near 106th Street and Forest Avenue, police said.

The men—all 23-years-old—were standing outside in near 106th Street and Prairie Avenue when a man approached them and opened fire, police said.

One man was shot in the groin and buttocks, police said, and another man suffered gunshot wounds to the foot and calf. Both were listed in “stable” condition at Advocate Christ Medical Center.

The third man was shot multiple times and was taken in critical condition to Stroger Hospital, police said.

An off-duty police officer saw the shooting and followed the gunman as he fled into an alley, police said.

The man began firing shots at the officer, who then fired his gun, police said. The shooter eventually got away, police said.

Police described the shooter as a man in his 20s who wore a black hoodie and styled his hair in dreadlocks.

A police helicopter scouted the area Sunday evening, according to unconfirmed dispatch reports.

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