Sparks from a passing semi-truck caused a spate of brush fires along Interstate 5 Tuesday night, the Whatcom County Fire Marshal’s Office said Wednesday.
The fires broke out along a 2-mile span of I-5 near Custer, said Mitch Nolze, a county fire investigator. Firefighters battled about 20 spot fires, he said, between mileposts 270 and 273.
A witness’s dashboard camera helped investigators determine the cause, Nolze said. With the video footage zoomed in, investigators could see sparks fly from a passing truck shortly before the fire started.
“It just happened to be the right combination of conditions and mechanical failure to do that,” Nolze said.
Investigators returned to the scene Wednesday morning and considered the possibility of arson, Nolze said. But they found no remnants of paper or any other signs of arson or reckless burning.
The fires caused no property damage other than the grass they burned, Nolze said. The scene was cleaned up by Wednesday afternoon.
Tuesday’s fires, Nolze added, are a reminder that dry conditions can cause brush fires even during the winter.