UPDATED 07/24/12 6:58 a.m.

CHICAGO (CBS) — One teenage boy was killed and 12 others were injured in Chicago just between 9 p.m. Monday and 5 a.m. Tuesday.

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As CBS 2’s Susanna Song reports, four of the victims were shot in Merrill Park, in the 2100 block of East 96th Street in the Jeffery Manor neighborhood.

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A 17-year-old boy was killed in the shooting, and two women – ages 34 and 30 – as well as a 21-year-old man – were wounded. They were all standing in the park as someone opened fire at 10:18 p.m. Monday.

Two people came out of a nearby gangway and started shooting – one with a rifle, the other with a handgun, police said.

The older woman and the 21-year-old man were both taken to Stroger Hospital of Cook County in stable condition, with gunshots to the abdomen and the left leg, respectively. The younger woman was shot in the leg and taken to Advocate Christ Medical Center in Oak Lawn in stable condition.

The 17-year-old boy, identified as Alixi Johnson of the 9600 block of South Merrill Avenue, was shot in the neck and was also taken to Advocate Christ, where he was later pronounced dead, according to the Cook County Medical Examiner’s office.

About 40 minutes earlier at 9:40 p.m., a 17-year-old boy was shot and wounded as he rode his bike in the 6000 block of South Winchester Avenue, in the West Englewood neighborhood. He was listed in good condition at Stroger Hospital after beign sh9ot in the leg by an unidentified man.

Two teenage boys – the younger just 13 – were wounded an incident a short time later in the 7200 block of South Artesian Avenue in the Marquette Park neighborhood.

At 10:03 p.m., the boys, 13 and 18, were standing on the sidewalk as a gunman approached on foot and opened fire from an empty lot.

The younger boy was wounded in the left thigh, and was taken to Advocate Christ in good condition. The older boy was driven to Holy Cross Hospital with two gunshot wounds to the upper back and a third to the right foot, and was reported in stable condition.

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Around 11 p.m., a 20-year-old man was shot and wounded as he walked down the 4000 block of West Augusta Boulevard, in the West Humboldt Park neighborhood. Someone in a dark-colored vehicle opened fire, police said.

The man suffered a gunshot wound to the right toe, and was driven by a family member to West Suburban Medical Center in Oak Park where he was reported in good condition.

At 11:18 p.m., a 26-year-old man and a 19-year-old woman were wounded in a drive-by shooting in the 12000 block of South Wallace Street, in the West Pullman neighborhood. Someone in a dark-colored sport-utility vehicle opened fire and wounded the man in the right arm and the woman in the left buttock.

The man was taken in good condition to MetroSouth Medical Center in Blue Island, the woman in good condition to Roseland Community Hospital.

Around 12:35 a.m. Tuesday in the 10100 block of South Parnell Avenue in the Washington Heights neighborhood, a 27-year-old man was shot in the right ankle. He was driven to Roseland Community Hospital in good condition following the shooting, which is believed to be gang-related.

Around 1:20 a.m., a 31-year-old man was wounded as he got into a car in the 7800 block of South South Shore Drive, in the South Shore neighborhood, when another man fired shots from a gangway. The man was taken to Roseland Community Hospital in good condition with a gunshot to the arm.

And around 4 a.m., a 28-year-old woman sitting in a parked car suffered a graze wound to the back, when someone in a light-colored sedan pulled up and opened fire in the 7000 block of South Wentworth Avenue, on the eastern edge of the Englewood neighborhood. She was taken to Stroger in good condition.

Later Tuesday morning, community activist Andrew Holmes is planning to hold a news conference, urging steps to stop the violence.

Holmes wants local radio stations to stop playing gangsta rap music, which he believes encourages young people to commit violent acts.

Holmes also says gangsta rap encourages a “no snitching” ethic that discourages people from reporting assailants to police. He pointed specifically to 17-year-old Chicago hip-hop artist Chief Keef, who has a song titled, “Never Snitch.”

“A lot of kids and a lot of teenagers are listening to this music, and it’s like it’s an education tool for them. But it’s not,” Holmes said. “And if the radio market would look at the lives instead of looking at their ratings, look at the lives that are being lost to people just using alcohol and drugs, listening to this music, going out committing crimes similar to this music. And just like the no-snitch – you’ve got a lot of people out here who don’t want to call in – ‘But I’m not a snitch.’ No, it’s not about being a snitch. And no disrespect to Chief Keef, but come with a different version of that, because look at the lives that are being lost.”

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Holmes says it is time for people to come together and help police solve violent crimes, and he is passing out fliers urging people to do so.