Firefighters responded around 2:15 a.m. to a report of a fire in the yard, which is shared by five companies in the 500 block of Brookside Drive, Battalion Chief Merlin Turner said.
The businesses include a pallet manufacturer, a roofing company and a landscaping business, he said.
"The fire started in the pallet area and damaged several of the businesses," he said.
Crews struggled to access the yard, which is bounded on one side by a creek.
It took Richmond fire and Contra Costa County Fire Protection District crews about three hours to knock down the blaze, which burned eucalyptus trees, several vehicles, a Bobcat tractor and other equipment, Turner said.
"There was extensive damage," he said.
No injuries were reported, and the cause of the fire remains under investigation.
Fire crews remained at the scene mid-morning today.