Investigators said the shooting started with a group of people attacking a man inside the Liberty 3 Laundromat on Chambers Street at about noon.
Police said Eudean McMillan, "Mama Dean," allegedly brought a gun into the business and opened fire.
A 16-year-old was hit by the gunfire. He remains in critical condition at an area hospital.
Adrienne Allen told Action News that it is her son, Koi, who was shot during the chaos.
"It's going to take a lot of prayers and a lot of recovery," she said/
Darryl Parker, 37, the man who was attacked, then took the gun and shot one of the alleged attackers, 21-year-old Geovahnie Fanfan, authorities said. A 15-year-old then took the same gun and shot Fanfan again.
Fanfan was taken to St. Francis Medical Center where he was later pronounced dead, police said.
"Not only do I have to deal with my son in the hospital, but the young man who lost his life is also a friend of my other son," Allen said. "No child had a gun. The adult is the one who brought the gun to the fight. And that's what I can't understand."
According to authorities, Parker and the 15-year-old are now charged with murder in connection with the shooting. McMillian is facing attempted murder charges.
The 15-year-old suspect is being held in the Middlesex County Juvenile Detention Center. Dean and Parker are being held in the Mercer County Correction Center pending detention hearings.