According to the Mission Viejo Patch (Saddleback College Fire Victim Identified), the kid who died in the fire was “21-year-old Saddleback College student Jacob Matthews of Lake Forest.”
As you know, he died of his injuries at the hospital, not long after the fire that occurred in "room 356 of the campus' BGS building.”
According to Orange County Fire Authority spokesman Jon Muir, the fire damaged only the lecture hall. Further,
Although the fire began near an air conditioning unit, the air conditioner did not cause the fire….Yeah, it was arson. They're not sure if Matthews was the arsonist.
See also Fire in BGS building at Saddleback College injures one (Lariat), which has been updated.