A fire erupted in Cuesta Grade, Calif. this Sunday and it was caused by a hot piece of metal from the brakes of a car descending a hill, according to California fire investigator Zach Nichols.

“It’s extremely common for a brake component or exhaust component to start a fire,” he said.

The fire spread across 10-acres. No injuries were reported, but some of PG&E’s power poles were burned in the fire and traffic delays occurred. This is the fourth vehicle related fire around this area this year.

Basically what happened was this: As drivers descend on the steep hill, they brake hard at the bottom to reduce their speed. That heats up the brakes and sometimes causes parts to fly off. The lack of rain in the area, combined with the loose heated metal caused the dry grasses to ignite into flame.

The fire department had found a piece of metal in a burnt piece of grass on the southbound gutter of the highway, and from there could determine where the fire had spread.