A fire official says a deadly wildfire that continues to spread near California's scenic Big Sur was started by an illegal campfire.

Fire information officer Deborah McClain said Tuesday that investigators determined the blaze started July 22 in an area of Garapata State Park where campfires are prohibited.

McClain says officials are still trying to determine who started the campfire and are asking for information from campers who were in the area before the massive blaze charred 67 square miles and destroyed 57 homes.

A bulldozer operator working the fire lines was killed last week in a rollover accident in steep, forested ridges.