San Diego, California (CNN) -- Despite having 21 years experience as a firefighter, Arthur Jackson was shocked by what he saw Tuesday -- piles of smoking ash located next to houses in pristine condition in this San Diego suburb.
Firefighters in California battle a fire that's being called San Diego's worst ever.
"It is just amazing how this fire selects whatever it wants and burns whatever it wants," he told CNN.
As utility workers focused on shutting off the flow of natural gas in the neighborhood, Jackson said he was focusing on keeping what's left intact.
"The priority now is to protect the houses they have," he said.
"There are a few hot spots that may not look like much, but might be right next to a house that has burned," Jackson said.
"That's what we are hitting, to make sure that more houses don't burn in the area." See dramatic photos of the destruction »
Despite toiling in 24-hour shifts, Jackson said he and his fellow firefighters were "holding up pretty good." Watch a report mapping the fires »
What weighed heaviest on them was not so much the physical exertion, but knowing they had failed to protect all of the structures, he said.
For some, the failure was more than a professional concern. "Some of the firefighters, their own homes have burned up," Jackson said. Watch Gov. Schwarzenegger describe 'a perfect storm' »
Meanwhile, the human toll from the fires is growing.
One person has died and eighteen firefighters have been injured.
More than half a million people have been forced to evacuate their homes in San Diego County, the hardest-hit part of the state. E-mail to a friend
CNN's Dan Simon contributed to this story.