A firefighter from San Diego has died while battling the Thomas fire in the Fillmore area of Ventura County, officials said Thursday, Dec. 14.

The firefighter, identified as Cory Iverson, was an engineer for Cal Fire based in San Diego, officials said. Authorities have not yet released details on how the accident occurred.

“I am very saddened to report that a firefighter fatality has occurred on the Thomas incident,” Cal Fire chief Ken Pimlott in a statement. “The incident is still unfolding, but in this world of fast moving information, it is important to me that only factual information be shared. To that end, I can confirm a fatality of a Calfire engineer from the San Diego unit has occurred. IMT 4, CAL FIRE Local 2881 and Southern Region leadership are working to support the Unit and his family, who have been notified.”

I am very saddened to report that a firefighter fatality has occurred on the Thomas Incident. Please join me in keeping our fallen firefighter and his loved ones in your prayers. – @CALFIRE_CHIEF https://t.co/lJjvOddchS pic.twitter.com/zylqSlsj3K — CAL FIRE (@CAL_FIRE) December 14, 2017

Pimlott said more details will be made available as they are confirmed.

“In the meantime, please join me in keeping our fallen firefighter and his loved ones in your prayers, all the responders on the front lines in your thoughts as they continue to work under extremely challenging conditions,” he said.

Earlier in the day, officials confirmed a firefighter sounded a “mayday” alert while working the fire after a “serious accident” occurred.

“Something did happen,” said Cal Fire deputy chief Scott McLean just before noon. “We’re trying to gather information as we speak … we’re in the fact-finding phase at the moment.”

A mayday call “means a firefighter is in trouble,” McLean added.

“It’s a very fluid situation,” McLean said. The Ventura County Fire Department confirmed the “mayday” call earlier Thursday.

Unconfirmed reports suggested the firefighter had been working in the 1700 block of Grand Avenue in the city of Fillmore.

Kuredjian added that “our helicopter was dispatched to assist.”

As of Thursday afternoon, the Thomas Fire was at 242,500 acres and 30 percent containment, with about 1,200 structures damaged or destroyed and 18,000 structures threatened, Cal Fire said.

The blaze began at 6:26 p.m. Dec. 4 in the Santa Paula/Ventura area, forcing tens of thousands of evacuations and destroying hundreds of homes. The fire fight has racked up about $74,760,500 to date, officials said.

Agencies throughout California offered their condolences on Thursday.

The Ventura County Fire Department on Twitter said it is devastated by the loss of a fellow firefighter and is sending prayers and condolences.

Teresa Benson, a forest supervisor for the Los Padres National Forest said the incident is a “tragic reminder of the dangerous work that our firefighters do every day.”

“The Thomas Fire has many unprecedented conditions and complexities that challenge the already demanding job of fire suppression,” she said in a statement. “I know I speak for us all in saying our hearts go out to our Cal Fire colleagues during this difficult time.”

This story is developing. Check back for updates.

#ThomasFire #Fillmore Firefighter DOWN in burn area, high priority – still trying to account for firefighters, 1721 Grand Avenue, request ALS ground base, MAYDAY CALL was made. — AI6YR – Ham Radio (@ai6yrham) December 14, 2017

#BREAKING: A #mayday call was made by a firefighter working the #thomasfire. Unknown condition. They are working on contact with group. All radio traffic halted except emergency traffic. — News Source LA (@NewsSourceLA) December 14, 2017