Hand and a friend were about to get on a MARTA transit system train when a man accused them of stealing his cell phone, said 18-year-old Diamante Drake, who said he was with Hand at the station. After the teens told them man they didn't have his phone, an argument began, Drake told WGCL-TV.
"Rueben told him to stop following us and was cussing at him," Drake said.
Then the man pulled out a knife and stabbed Hand in the neck, Drake said.
"We tried to catch him and bring him to the police but he started swinging the knife at us," Drake said. "We seen little Rueben on the ground bleeding."
MARTA spokesman Lyle Harris confirmed that the slaying happened early Saturday. But he said MARTA police are not identifying the victim because he's a juvenile.
"Everybody loved him. You know, he touched everybody," Hand's mother Deunya Taylor told WSB-TV. "I really just still don't believe that my baby's gone."
Taylor told WGCL-TV that her son hadn't asked permission to go downtown to ring in the new year, and hadn't told her where he was going.
Family members say police have surveillance video of possible suspects, and family members hope the killer will turn himself in.
Authorities said another victim was stabbed during the New Year's Eve festivities at nearby Underground Atlanta late Friday night. That victim was taken to the hospital in stable condition.
More than 100,000 people gathered downtown for the Peach Drop on Friday evening.