Firefighters in Southern California have been busy battling five brush fires since Tuesday, according to the L.A. Times. 

The Guiberson fire, the most threatening of the five fires, grew to 16,400 acres Thursday morning and was still burning with 40 percent containment, according to the Ventura County Fire Department.  The fire prompted Gov. Arnold Schwarzenegger to declare a state of emergency in Ventura county Tuesday.

The Guiberson fire, which reportedly broke out after a large pile of manure combusted from the high heat, reported by the Ventura County Star, has destroyed two outbuildings.  Eight fighters have suffered minor injuries, according to the Ventura County Fire Department.  

The Ventura County Star reported 864 firefighters on the scene Wednesday evening with more on the way, and said the fire is expected to be fully contained by Saturday.

Meanwhile, officials arrested a 16-year-old boy on Wednesday on suspicion of starting the Crafton fire, according to the San Bernardino County Sun. The fire has burned 465 acres and is 60 percent contained.

According to the L.A. Times, the Inland Empire fires were fully contained Wednesday.

The L.A. Times also reported Wednesday that U.S Forest Service firefighters said the Station fire in the San Gabriel Mountains would be fully contained by Thursday night. The fire started nearly a month ago and is 94 percent contained.