The fire started just before 1:30 a.m. in a second floor unit at 500 Wimbelton Court. Firefighters arrived to find flames shooting through the roof of at least one unit.
More than 50 firefighters worked for close to an hour to bring the blaze under control, at times taking breaks from the intense flames.
Some residents chased out of their apartments by the flames had nowhere to go but their balconies to escape. As the fire worked its way closer to the balconies, some residents jumped from their second and even third story balconies to escape. One woman who jumped from her third floor balcony was hospitalized with broken wrists.
"One of the people went and got a mattress and put it under the balcony where everybody was," said Amber Robards, who lives nearby.
Neighbors raced to help residents fleeing the flames.
"One person jumped out on the mattress, so we moved it over to the other one where there were four people and completely black some coming out of the apartment," Robards said.
Three children, ranging in age from 7 to 11, were also rushed to the hospital for smoke inhalation. Emergency responders said the injuries to all four victims were not life-threatening. Meanwhile, some residents apparently slept through the fire.
"We do know that our units carried out several rescues for multiple occupants that were still at home in bed when the fire occurred," said Sgt. Salvador Melendez with Louisville Fire & Rescue.
The building, which housed 12 units, was evacuated, and residents were asked to leave until the damage can be assessed.
At least four of the apartment's 12 units were heavily damaged.
Just after Noon on Thursday, investigators made the official determination that unattended cooking sparked the fire.
There was another fire at the same apartment complex in February of 2010. The cause of that fire was later determined to be electrical.