A helicopter flies over a back burn on a ridge south west of Cachagua as firefighters battle a wildfire in east Carmel Valley, Calif., Monday. Higher humidity and lower temperatures on Monday helped firefighters battle the destructive wildfire near the scenic Big Sur coast.
(Photo: David Royal, The Monterey County Herald via AP)

A devastating coastal California wildfire that’s destroyed 57 homes and caused the death of a bulldozer driver was sparked by an illegal campfire, authorities said Tuesday as they asked for help finding the culprit.

Whoever built and then abandoned the fire around July 22 in the Garrapata State Park could face criminal and civil penalties for sparking the blaze, which has now burned more than 43,000 acres near Carmel, Big Sur and the Pebble Beach golf resort. Authorities said hikers who reported the fire had to first climb up to a ridge top to get mobile phone reception.

“We understand the devastation and hardship this incident has caused,” CALFIRE Battalion Chief Jonathan Cox said. “We appeal for anyone who was in the area of origin to please come forward and give any information they have, no matter how inconsequential they may believe it to be. It could be instrumental in this investigation.”

The campfire was started about two miles from the main road, in an area closed to camping, state parks officials said.

High temperatures have complicated the battle against the fire, which is sending a massive plume of smoke into the sky about 120 miles south of San Francisco. The fire is burning in steep, rugged coastal terrain.

The fire is a top national priority: 510 fire engines, 51 water tankers, 72 bulldozers, 17 helicopters, six air tankers, and more than 5,400 firefighters are battling the blaze, which is about 18% contained. Carmel-area residents have posted pictures on social media showing the ash dusting surfaces and the smoke clouding the sky.

Calif. Gov. Jerry Brown has declared a state of emergency to free up resources for firefighting efforts, and several neighborhoods remain evacuated. Homes in the area are spread amongst the hills, linked by narrow roads winding through the tree-and-brush-covered landscape parched by the state’s ongoing drought. Due to the drought and fire risk, campfires outside of campgrounds are barred in large sections of California.

“Even though it may be a comfort, it’s not worth the risk of having a campfire and the unintended consequences,” said Don Jaques, a U.S. Forest Service fire spokesman. “The risk that’s out there is just too great.”

California is a tinderbox of dead trees, which is fueling the fire risk. A new federal report says 26 million trees have died in the southern Sierra Nevada since October 2015, and those deaths are in addition to the 40 million trees that died across the state from 2010 to October 2015, bringing the total to at least 66 million dead trees. Four straight years of severe drought in California, a dramatic rise in bark beetle infestation and warmer temperatures are leading to historic levels of tree die-off, according to the report.

Firefighters said about 300 new wildfires were sparked last week in California, with virtually all of them quickly contained. Large portions of California are considered at “above normal” for wildfire risk, as is northern Nevada, northwestern Utah, southeastern Oregon, and southern Idaho and Montana, according to the National Interagency Fire Center’s Aug. 1 prediction.

Anyone with information about the Soberanes Fire is asked to call: 1-800-468-4408.