Two structures were destroyed in a 5-acre grass fire Wednesday afternoon in an area off
Altamont Pass Road near the Altamont Landfill.
Battalion Chief Stephanie Radecke of Alameda County Fire said heat from a catalytic converter or a diesel particulate filter on an utility worker's vehicle may have set some grass on fire.
The fire extended to some ranch property where an outbuilding and a small home were destroyed before the flames were extinguished at 3:01 p.m.
No one was injured in the blaze, Radecke said.