POULSBO — A trailer hauling bark and wood fiber — called “hog fuel” — to Port Townsend caught fire Friday morning, causing a traffic backup on Highway 3.

The northbound roadway reopened at approximately 10:30 a.m.

The 55-year-old driver was transporting the bark and wood fiber from Tacoma, driving northbound, when he noticed sparks in his mirror.

After pulling over, the driver tried to put out flames with a fire extinguisher, but it was not enough, Poulsbo Fire spokeswoman Jody Matson said. The Poulsbo Fire Department responded to the fire just after 9 a.m.

By 10 a.m., emergency crews were looking for any “hot spots” that may reignite the fire, Matson said.

The trailer is a single compartment. If the fire had been allowed to burn much longer, it could have been a bigger problem, Matson said.

The material in the truck was to be used for fuel at a mill.

Foam was sprayed into the single-compartment trailer from the top to put out remaining heat sources. Crews scraped out the hog fuel from a hole in the side of the trailer.