MARTA, or Metropolitan Atlanta Rapid Transit Authority, is the city transit system.
The suspects include a 16-year old male whose name is not being released because of his age and two brothers, Zantavious Sanchez Scott, 20, and Jarquez Scott, 19, MARTA police said.
Transit police said they are continuing their investigation and searching for others who may have been involved. They said they have warrants for at least two other suspects, ages 19 and 14.
"We are continuing our investigation into this unprovoked and senseless act," said MARTA Police Chief Wanda Dunham. "We advise anyone who may have been involved to turn themselves in. We intend to find you and will prosecute you to the full extent of the law."
The attack happened April 16 as the two Delta employees rode a southbound train toward Atlanta's Hartsfield-Jackson International Airport, police have said. As many as 20 to 25 people attacked the two men.
One of the victims said teenagers hit him with a soda can before pushing him down and taking his billfold. He reported a cut next to his left eye from the assault.
The other Delta employee said he received a cut on the lip and reported nothing stolen.
According to accounts from the victims and witnesses, the incident happened shortly after Atlanta police dispersed a large group of young people who had been attending a party at a club near downtown Atlanta. Some of the youths boarded a MARTA train a few blocks away.
As the train headed south, several suspects attacked the two Delta employees, and then exited the train at another station, police said.
One of the victims said he was not left shaken by the attack.
"I think you have to be vigilant and you have to be careful, but that's true wherever you go," said the man, whose name was not released. "But I've never felt unsafe on MARTA. I've ridden it before, and I will ride it again in the future. Actually, I rode it after this happened."