Chicago police said the shooting happened in the West Pullman neighborhood's 12100-block of South Harvard Avenue just before 11:40 a.m.
Neighbors who did not want to appear camera told ABC7 they saw a car driving toward the victim's USPS truck before hearing at least 10 shots in broad daylight.
Police said the offender, identified only as male, approached a 48-year-old woman, took out a gun and fired shots. She suffered multiple gunshot wounds to her body.
The woman, a postal worker, was taken to Christ Hospital in very critical condition, Chicago Fire Department officials said.
Police said the victim was later pronounced dead at the hospital. The Cook County Medical Examiner's Office identified her as Octavia Redmond.
Redmond's USPS truck remained on the scene, and police said the offender fled in a vehicle westbound on 121st Street.
A flag hung at half-staff outside a South Side union hall to honor Redmond on Friday night. She was a wife and grandmother who worked as a letter carrier for more than 15 years.
"They need to be prosecuting them. We are federal employees. How dare you? And, you just think you can get away with it? My members are scared to go to work," said National Association of Letter Carriers President Elise Foster.
People who knew Redmond are left heartbroken.
"It's a loss of life, you know? She's not going home to her family," Foster said. "I know her husband. He's a letter carrier, also assistant union steward at the station. She was just a great person."
Redmond's impact is also felt by those on her route.
Kim Sanders, who works a group home a few blocks down, said she and other neighbors are devastated and shocked that a shooting happened on a block that is normally quiet.
"It can't be true, not in this area, not in this block, because it's a lot of older people. And all of us know each other," Sanders said. "My heart is shattered, because there was a nice lady. She'd just come up and down the block and deliver the mail, didn't bother nobody."
Sanders said Redmond always had a smile on her face.
"We all knew her, yes. She was like a mother to the neighborhood," Sanders said. "She'll walk up to me. She's like, 'Have a good day,' sometimes. And she'll see the clients and sometimes give them a sucker or something. Like, she was a very, very good mail lady."
U.S. Postal Inspection Service Chicago Division inspectors are offering a reward up to $250,000 for information leading to the shooter's arrest and conviction.
"One of our own, a postal employee, we take it as seriously as anything, because this is why we're here," said Spencer Block with the U.S. Postal Inspection Service
You can call 877-876-2455 to report information.
No one is in custody on Friday night, and there's no word yet on a motive. Area Two detectives are investigating.
"It was not worth it. You took a beautiful soul," Foster said.
Grief counselors will be made available Saturday morning at the victim's home post office in Roseland.
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