Lisa Shubert, 42, of 32 Colbert School Road, and Terry "T.J." Cotton, 39, of 46 Madison Ave., got trapped by the fire in a shed behind the mobile home Shubert rented just outside the Madison County town, county Coroner Michelle Cleveland said.
Colbert and Hull volunteer firefighters, who responded shortly after 1 a.m. Sunday, pulled both victims from the flames, but resuscitation efforts failed.
Shubert's boyfriend, Jerry Scott Payne, 39, also of 32 Colbert School Road, escaped the building but was burned over 60 percent to 70 percent of his body, said Jimmy Patton, chief investigator for the Madison County Sheriff's Office.
Madison County first responders treated Payne on the scene, and he was flown by helicopter to an Atlanta hospital.
Investigators are not exactly sure what sparked the fire, but firefighters have speculated that one of the three adults might have put a cigarette out on the concrete floor of the storage room, igniting a fire that set off the gunpowder.
The fire started near the front door, preventing them from escaping, said Tim Wyatt, chief of the Colbert Volunteer Fire Department.
"We had five guys there within a minute of the call, but there was nothing they could do," Wyatt said.
Shubert, Payne and Cotton had a yard sale Saturday and had planned to leave their stuff out in the yard so they could continue the sale Sunday, witnesses told firefighters. However, sometime after midnight, they heard it was going to rain, so they rushed out to move their things into the storage shed, Wyatt said.
The late Pat Patterson, who had owned the house and shed Shubert was renting, had used the shed as a gun shop and later converted it to storage after moving his firearms repair business into his basement.
An old wooden cabinet in the shed "looked like it had several cans of gunpowder in it," Wyatt said.
Wyatt and fire investigators are hoping to search through the shed today to figure out exactly how the fire started.
Wyatt, Cleveland and Patton said they consider the fire accidental, though the state fire marshal is investigating the official cause, and the victims' bodies were taken to the Georgia Bureau of Investigation crime lab for autopsies.
Colbert volunteer firefighters seldom deal with fire fatalities, and many of the men were shaken.
"It was probably one of the worst we've seen," Wyatt said. "I mean, we've worked bigger fires, but this was the worst just in terms of the fatalities and just the situation. It's not very often that we work fatal fires."
The department had a debriefing meeting Sunday evening to go over what happened that morning.
"People just got some stuff off their chest," Wyatt said. "But everybody's doing OK now."
In town Monday, friends and Colbert residents gathered at the Bread Basket deli, where Shubert was a regular.
"Especially in a small town like Colbert, everyone knew her," said Colbert resident Melissa White, who was eating lunch at the Bread Basket on Monday.
Everyone knew Shubert from her mail route or just from around town, and everybody liked her, said Tonya Maddox, a former neighbor of Shubert's.
"She was just the type of person who would do anything she could to help you," Maddox said.