Fire crews from multiple agencies battled a vegetation fire northwest of Vacaville in Solano County on Monday.
The fire broke out just before 11 a.m. near Mix Canyon and Sky Ranch roads.
The fire has burned about 150 acres and is 60 percent contained, according to Cal Fire.
Fire officials say 20 mph winds proved to be a challenge, as conditions continue to cause spot fires outside containment lines.
"Today is challenging," Cal Fire Captain Joe Fletcher told FOX40 Monday. "The roads are narrow. Access is tight. And, terrain is very steep here."
The blaze, which is being called the Sky Fire, was reportedly started by a car. It is not known how the car started burning.
No evacuation orders have been placed at this time. However, twelve homes are under voluntary evacuations.