A blown transformer in the 43000 block of Sierra Drive is the suspected cause of a fire that quickly spread to the hillside vegetation. The fire began about 10:30 a.m. today, and local engines were on scene within minutes of the 911 call. Several other crews arrived within a half hour to assist. Two Cal Fire spotter planes kept an aerial eye on the fire while a helicopter with water bucket made some drops. The fire was contained quickly.