UPDATE (3 p.m.) - CAL Fire SLO says the fire is now 100% contained.
Crews are still mopping up the scene and Hwy 166 is expected to be fully open around 3:45 p.m.
The fire burned approximately 54 acres.
(1:30 p.m.) - CAL Fire SLO told KSBY that the fire is holding within its containment lines.
Crews say high wind speeds and dry brush were key factors in the start of the fire.
Additionally, crews are using retardant, roads, a bulldozer line and a hand line. CAL Fire SLO also says there was an aircraft assisting.
The fire is holding at approximately 25 acres.
(1 p.m.) - CAL Fire SLO tweeted that the fire has burned over 25 acres in grass and light brush.
Firefighters say it has potential to spread 100 acres.
The flames are spreading at a moderate rate and conditions are windy.
Hwy 166 is closed east of Santa Maria.
The fire is currently burning on the south side of Hwy 166.
(12:40 p.m.) - Firefighters say the flames are spreading. The fire is now close to 25 acres and is getting closer to roadways.
(12:20 p.m.) - Firefighters are responding to reports of a vegetation fire in Santa Maria.
According to CAL Fire SLO's Twitter post, the fire is off of Hwy 166 and Wineman Rd.
Firefighters are responding to the area and say no structures are threatened at the moment.
CAL Fire has requested that CHP closes down the roads from US 101 to Bull Canyon.
This is a developing story.