Marquetta Campbell was out celebrating a friend's birthday when her family says an argument with two other people turned deadly.
Campbell leaves behind two daughters, ages 9 and 2.
Police were not releasing many details Sunday, but they indicated they were talking to a person of interest.
Family and friends say the incident started at a nightclub in Matteson and ended at a sandwich shop in nearby Chicago Heights.
Chicago Heights detectives continued to question a man and a woman Sunday in connection Campbell's death. Investigators were calling her murder personal.
The family of the 26-year-old woman says she was looking forward to the holidays.
The victim's mother, Joann Campbell, clinged Sunday to close friends for strength and comfort as she struggled to cope with the murder of her daughter.
"I've got to go bury my baby," she said tearfully. "She was more than a daughter; she was my best friend. I feel sorry for her kids. She was a good person, the best friend you ever want to have," Joann Campbell said.
It appeared Sunday evening that what ended violently at 2:30 a.m. outside a suburban sandwich shop had begun hours earlier at a nearby club where Campbell and a group of friends had gone to celebrate the birthday of a girlfriend. While there, friends say Campbell exchanged heated words with another patron after dancing with that woman's boyfriend.
Campbell and her group reportedly left the Matteson sports bar to eat, ending up at the Big Boy submarine restaurant.
"The girl followed her all the way up here and sat out here as she came out of the restaurant and ran up and stabbed her," family friend Linette Bell told ABC7 Chicago.
Witnesses tell police as several of Campbell's friends came to her aid, others tried to restrain her attacker. That's when the woman's boyfriend who was also in the parking lot opened fire, striking Marquetta in the head and wounding two other men.
"I don't think it was a mistake. From what I hear, it was retaliation for them beating up his girlfriend or something like that," said Willie Bell, a friend of the victim.
Campbell was pronounced dead at the scene.
Investigators had not determined the exact motive for the slaying Sunday evening. They, along with the victim's family who gathered across the street from the crime scene, said the attack appeared to be personal.
"She was the backbone of our family. She was strong. She was the sweetest person," cousin Brandy Smith said.
Campbell, who worked as a certified nursing assistant, was remembered Sunday as generous and kind.
Her mother said she was waiting for justice and jail time for her daughter's killers.
"I hope that they just stay in there for the rest of their life. That's all I want," said Joann Campbell.
The two other shooting victims, both men, received non-life threatening wounds. Police say no one else is being sought for the attack.
No charges have been filed in connection with Marquetta Campbell's murder.
