LOS ANGELES — A brush fire possibly sparked by an overturned big rig near Pyramid Lake in northern Los Angeles County burned about 20 acres of vegetation Friday.

The Los Angeles County Fire Department received a call around 10:48 a.m. Friday about a fire burning next to an overturned big rig and construction excavator on Cascade Wonderland Highway, Officer Geovanni Sanchez told City News.

The truck driver was evaluated at the scene for minor injuries.

By noon, the fire had spread to about 20 acres, from an initial size of about 3 to 5 acres.

Crews from LACoFD and Angeles National Forest responded to the fire along the northbound Golden State (5) Freeway south of Vista del Lago. Several lanes of the freeway were blocked, creating a miles-long backup.

Authorities have not confirmed the cause of the fire.