Fire investigators have determined that the cause of Monday's White Fire was accidental.
The White Fire burned through nearly 2,000 acres of the Santa Ynez Valley and parts of popular campgrounds and trails.
Thousands of campers and residents were forced to flee on Memorial Day.
The Los Padres National Forest law enforcement and the District Attorney's Arson Task Force determined the blaze was not set on purpose.
"This is in fact a terrible, horrible accident and that there isn't an arson connected to this fire," said District Attorney Joyce Dudley.
Investigators found out that a legal cooking fire got out of control and it took fire crews four days to contain it.
"Grilling out is an American tradition, it's one of the greatest things in the world, but you have to be very careful. This time of year, in particular this year, is extremely dry," said Pancho Smith, district ranger.
Investigators do not know whose fire it was that sparked the blaze at the White Rock day-use area, but they are still looking.
"We'll try to determine who the person was and to determine that there wasn't any criminal intent in the matter. We don't believe there was. It very much appears to be accidental, but we will go forward with that," said Smith.
Although it was an accident, the damage was significant. Many popular areas for summertime camping and hiking will be closed until the land is safe once again.
The fire is contained but is still burning in some places. Fire crews will remain in the Santa Ynez Valley to make sure it doesn't spread.
Sites west of the Lower Oso day-use area will be open Monday, June 3.