A couple whose gender reveal ceremony sparked a Southern California wildfire that killed a firefighter last year were charged with involuntary manslaughter, authorities announced Tuesday.

Refugio Manuel Jimenez Jr. and Angela Renee Jimenez pleaded not guilty Monday to charges involving the El Dorado Fire, San Bernardino County District Attorney Jason Anderson announced at a news conference.

The charges included one felony count of involuntary manslaughter, along with other felony and misdemeanor counts related to the fire.

The El Dorado Fire erupted on Sept. 5 when the couple and their young children staged a baby gender reveal at El Dorado Ranch Park in Yucaipa, at the foot of the San Bernardino Mountains.

A smoke-generating pyrotechnic device was set off in a field and quickly ignited dry grass on a scorching day. The couple frantically tried to use bottled water to douse the flames and called 911, authorities said.

Strong winds stoked the fire as it ran through wilderness on national forest land, about 75 miles east of Los Angeles.

Climate Change Making Wildfires Harder to Fight

Extremely dry conditions and heat waves tied to climate change have made wildfires harder to fight. Climate change has made the West much warmer and drier in the past 30 years and will continue to make weather more extreme and wildfires more frequent and destructive.

On Sept. 17, flames overran a remote area where firefighters were cutting fire breaks, killing Charles Morton, the 39-year-old leader of the elite Big Bear Interagency Hotshot Squad. Morton had worked as a firefighter for 18 years, mostly with the U.S. Forest Service.

The blaze injured 13 other people and forced the evacuations of hundreds of residents in small communities in the San Bernardino National Forest area. It destroyed five homes and 15 other buildings.

The blaze blackened nearly 36 square miles (92 square kilometers) of land in San Bernardino and Riverside counties before it was contained on Nov. 16.

The fire was one of thousands during a record-breaking wildfire season in California that charred more than 4% of the state while destroying nearly 10,500 buildings and killing 33 people.

The couple were released on their own recognizance pending a Sept. 15 court date.