A San Diego County Fire truck sits parked amid smoke from a nearby fire.
A San Diego County Fire truck. (Photo courtesy of Cal Fire San Diego)

 Containment of the Thorn Fire in rural southeastern San Diego County is now 95% with the acreage burned holding at 1,234 acres, officials said Sunday.

Four structures were reported damaged or destroyed, but no further details were available. No injuries were reported.

“Firefighters worked hard throughout the day, improving and strengthening containment,” according to a late Saturday update from Cal Fire San Diego. “Patrolling and monitoring for hotspots will continue into the night.”

The wildfire started Wednesday near the Buckthorn and Clover trails in the Live Oak Springs neighborhood of Boulevard. Driven by the sweltering heat wave, the fast-moving flames initially spread south of Interstate 8 and north of Campo Road, according to Cal Fire.

Extreme heat persisted Thursday, with temperatures exceeding 100 degrees.

Traffic and local access initially impacted I-8, reducing it to one lane in both directions. Those closures were lifted at about 2 p.m. Friday, according to the California Highway Patrol.

The cause of the fire remains under investigation.