It looks like a fire bug is responsible for a destructive fire at Harris Ranch feedlot near Coalinga.
It broke out just after 4 a.m. Sunday.
When firefighters arrived, they found 14 tractors and several trailers on fire.
Fire crews put it out in about 45 minutes.
Then they called in arson investigators from Cal Fire and the Fresno County Sheriff's Office.
"Everything is on the table right now. They don't know. First they have to figure out how the fire started and they go from there. I talked to one of the arson investigators who said they could be there for a long time," said Deputy Chris Curtice with the Fresno County Sheriff's Office.
Investigators are looking through surveillance video for clues.
A spokesman for Harris Ranch says the fire will have no impact on daily operations.