US Forest Service officials said the death occurred in the San Bernardino National Forest, where firefighters were trying to put out the El Dorado blaze.
The cause and circumstances of death are under investigation.
The identity of the firefighter has not yet been revealed, pending notification from the family.
“Our deepest condolences go out to family, friends and fellow firefighters during this time,” Forest Service spokesman Zach Behrens said in a press release.
The wildfire began on September 5 when a family visited El Dorado Ranch Park and used a pyrotechnic device to reveal the gender of their unborn baby via colored smoke or fireworks.
But the small explosion quickly set off a fire that the family couldn’t put out.
Officials with the California Department of Forestry and Fire Protection, or Cal Fire, said Thursday that the El Dorado fire has now burned more than 19,000 acres and destroyed at least four homes.
More than 1,300 firefighters attempted to bring the blaze under control and at least 12 of them were injured.
Cal Fire officials said earlier this month that the family had cooperated with authorities, but no arrests had been made.
In 2017, a gender reveal stunt by an Arizona Border Patrol officer sparked a massive wildfire that burned 47,000 acres of grassland in two weeks.
The officer pleaded guilty to accidentally starting the fire and, as part of a plea deal, agreed to pay $ 220,000 in restitution.