Octavia Johnson, the boy's aunt, said Ja'Marr Tiller, who loved to run, climbed out of bed at his Mount Pleasant home Sunday evening, went down a flight of stairs and slipped out the back door.
Deandra Tiller, the boy's mother, returned home from running an errand to find him on the ground with his clothes torn off, covered in dog bites.
"She came in the house screaming, 'A dog has killed my son!'" Johnson told The (Charleston) Post and Courier.
Johnson performed CPR until paramedics arrived. "His eyes flickered to life, and there was some movement for a second," she said. "It's so tragic."
Ja'Marr later died in the hospital.
The two dogs roamed the area, but didn't belong to anyone, Johnson said. Charleston County Sheriff Al Cannon described them as "yard dogs."
"They were big dogs," Johnson said. "But we had never had any problems with them."
The dogs were taken into custody by Animal Control, although The Post and Courier reported there were no immediate plans to put the animals down and no charges had been filed.
Ja'Marr's death follows the April 20 death of a 2-month-old boy attacked by a dog in Ridgeville. That infant's father, Quintin McGrew, was charged with homicide by neglect.