SAN DIEGO – A fire on a semi-trailer prompted the closure of lanes Wednesday on westbound Interstate 8 in the Alpine area, California Highway Patrol said.

The fire of unknown origin was reported just after 4:30 a.m. on the freeway near Tavern Road, the agency’s traffic incident log shows. The result led to the closure of all westbound lanes of the freeway in the area of Tavern Road with traffic being diverted off at West Willows Road.

Fire damage burned up the middle of the semi-trailer and flattened the tires, according to CHP. Crews were seen extinguishing what remained of the blaze shortly before 6 a.m.

The left lane of westbound I-8 at West Willows Road reopened as of about 6 a.m., Caltrans said in a tweet. It is not yet clear when the rest of the freeway will reopen to traffic.

No further information was immediately available.

See more information on road conditions, including a live traffic map, on the FOX 5 San Diego traffic page.