SAN BERNARDINO, Calif.—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 …