The shooting occurred at about 9:30 p.m. at The Connect store in the 500-block of East 130th Street. The store, which is near the city's Altgeld Gardens neighborhood, sells groceries and cell phones.
Ihab Arafeh, 46, a cell phone accessory wholesaler, was among the victims. He died as he made a late night delivery to the convenience store. His son Zaid Ihab Arafeh is trying to cope.
"I have four brothers I have to take care of now. I have my mother. I have to be strong. Everyone is telling me to be strong 'cause I'm the oldest. And it's just hard," he told ABC7.
The Cook County medical examiner confirms Michael Banks, 30, and Alex Spikes, 17, are also among the dead. A 25-year-old victim remains unidentified.
The two people who were injured -- a 17-year-old boy and a 39-year-old woman -- were taken to area hospitals, treated and released.
Brandon Phillips, who sells cell phones at The Connect, told ABC7 he believes the four men killed may have all been his co-workers.
"They ran up there and shot them. They didn't try to rob them or nothing," Phillips said. "It's crazy. It's hard to believe, especially somebody you were just with yesterday. I was with them every day, you know?"
Phillips and customers say that one of the victims was an armed security guard whose white Cadillac they say has been parked in front of the crime scene since Wednesday night.
Witnesses say several gunmen walked into the store and opened fire during what could have been an attempted armed robbery. Police say two store employees returned fire during the gunfight inside the store which sells cell phones, blue jeans, beauty and dollar store items to area residents.
"Supposedly there was a dispute, and some people just came in and shots were fired back and forth," said Ald. Anthony Beale, 9th Ward.
"I knew the people that worked there. Like I said, it is a sad situation where I don't want to elaborate too much, because I'm kind of shocked myself. This is a shock for me going to work. I need protection for myself," said Jamiel Kern, a customer.
"They treated me with the utmost respect, everyone around here. No one can say a bad thing about them at all under no circumstances," said Trina Brown, a customer.
Police say several weapons were involved and some were recovered at the scene. Several people are in custody. While they are all being held at Area 2, none have been charged as of Thursday afternoon.
Police are said to be reviewing surveillance tape from a video camera inside the store that captured the several-minute-long shootout that started when store employees fought back against their would be robbers.
In the meantime, Zaid Ihab Arafeh is absorbing the loss of his father.
"I was with him yesterday, but I wish I was with him when we left from work. Somehow I just wish I could have changed something," he said.
There was no word on when the store will re-open.