UPDATED 02/29/12 11:21 a.m.

CHICAGO (CBS) – It was a deadly night for Chicago teenagers, with a 15-year-old girl dead as a result of a hit-and-run accident, and a 15-year-old boy killed by a gunshot.

As CBS 2’s Susanna Song reports, around 9:15 p.m. Tuesday, the girl was running across the street in the 8000 block of busy South Ashland Avenue in the Auburn-Gresham neighborhood, when a light-colored minivan struck her.

LISTEN: WBBM Newsradio’s Bernie Tafoya reports

The driver stopped for a moment, then sped off.

The girl, identified as Alliyah Kalimullahdunn of Harvey, was initially taken in serious condition to Advocate Christ Medical Center in Oak Lawn. She was pronounced dead half an hour later.

One man, who asked not to be identified, said he saw Alliyah lying on the ground after the accident.

“When I got to corner, I see a girl laying on the street, and I see a van parked,” he said, “and a guy got out of van, looked back, and then he jumped back in van, made a right at this corner and took off.”

The man said he was on his way to tell police what he saw.

“People were running up to her and she was laying on the street,” he said.

Neighbors say the stretch of Ashland Avenue where the accident happened is always busy with automotive and pedestrian traffic.

“This street right here between 81st and 80th is a really busy street, and people are not slowing down. They’re driving faster than ever,” said neighbor Renita Burley. “People tend to come out of the CVS… instead of going to the corner, they’ll run in the middle of the street trying to beat traffic before the light changes.”

Alliyah’s home in Harvey is lived 11 miles away. Her friend a few doors down was shocked to hear the news of her death.

“That’s crazy,” said the friend, Sharae Holloway. “She should have been at home somewhere.”

It’s unclear why Alliyah was in the Auburn-Gresham neighborhood Tuesday night.

Her principal at Thornton Township High School said she had just transferred to the school in January as a junior.

“She was a good person, and she was sweet,” Holloway said. “If you needed help anytime, she always helped you. She was fun to be around.”

Added the man who planned to report the incident: “It’s really sad that people can do something like that and have the audacity to pull off, and take a human life.”

The witness described the van as being gray and black although police say it was light-colored.

Meanwhile, around the same time in the Southwest Side’s Marquette Park neighborhood, a boy was shot and killed as he walked in the 6800 block of South Rockwell Street.

The boy was walking alongside a 16-year-old girl when a gunman got out of a light-colored sedan and opened fire, police said.

Earlier reports placed the shooting about a block away in the 2700 block of West Lithuanian Plaza Court.

The boy, Albert Guyton of 7600 block of South Prairie Avenue, was pronounced dead at 10:04 p.m. at Advocate Christ, according to the Cook County Medical Examiner’s office. was shot multiple times. The girl was not hit by the shower of gunfire, and managed to escape.

Police suspect the attack as gang-related.

The gunman fled the scene and was not in custody as of early Wednesday, police said.

The Sun-Times Media Wire contributed to this report.

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