When he emerged from his car, a witness said, he had ammunition draped across his chest "like Rambo." He shot more people inside the sprawling warehouse, police said, sending other co-workers scattering as gunfire rang out. One man injured himself trying to flee.
Kramer then made his way to a trailer where he killed himself, ending the rampage. Police declined to say what his motive was, but the explosive devices indicate his destructive intensions. The explosives weren't used and all six victims survived their wounds.
"It was chaos," said David Titus, a FedEx truck driver who was waiting to get into the center just before 6 a.m. when he saw a man walk up and shoot a security guard in the abdomen.
He said the man then went inside and more gunshots rang out from inside the building.
"Everyone was running, ducking and hiding, trying to get out of there," Titus said.
FedEx clerk Liza Aiken said she was working when she heard something drop, looked to her left and saw the gunman.
"He had bullets strapped across his chest like Rambo" and held a knife, Aiken said.
By around 6 a.m., dozens of officers from multiple agencies swarmed the center about 25 miles north of Atlanta that sorts packages and loads them onto vehicles for delivery. The police secured the perimeter and blocked roads leading to the FedEx center. Dozens of workers were taken by car and bus to a skating-rink parking lot to call relatives for rides. Some family members got out of their cars and hugged the workers.
The suspect, identified by police as the 19-year-old Kramer of Acworth, worked as a package handler at the sprawling facility, Cobb County police Sgt. Dana Pierce said. Investigators have an idea of what his motive may have been, but they declined to disclose it.
The package center was shut down and the entrance surrounded by crime-scene tape. The full investigation was time-consuming because authorities had to search every part of the 500,000-square-foot facility for evidence.
Later in the day, the man's car was towed from the scene and employees were allowed back to pick up their vehicles.
Three of the victims were critically wounded, though only one remained in critical condition by late Tuesday afternoon.
A 28-year-old man who underwent surgery was in critical condition late Tuesday, while a 52-year-old woman who underwent surgery was upgraded to stable, police said. A 22-year-old man's condition was also upgraded to stable.
Among the others wounded were a 42-year-old woman and two men, ages 38 and 19.
Another man hurt his knee trying to flee the shootings.
The gunman's father, Scott Kramer, released a statement expressing the family's condolences to the shooting victims.
"Our prayers are for their complete and speedy recovery. Our thoughts are also with all the workers at FedEx who were affected by Geddy's actions. We make no excuses for his actions and are shocked and devastated by them. There really are no adequate words at a time like this," Kramer said.
The company offered no details about the attack, saying only that it was "focused on the needs of our team members and cooperating with the law enforcement investigation of this tragedy."