High, eratic winds are driving the flames and making it difficult to get fire suppression aircraft into the area. This is in an area with dense forestation. Several local schools were closed. One school first used as an evacuation site was subsequently evacuated.
Many people in the area have large livestock that need to be evacuated as well.

The fire started at about 5:30 a.m. Thursday off Summit Road near Loma Prieta Road in the Santa Cruz mountains.

NBC11 coverage

The flames are being fanned by gusty winds out of the northwest that are predicted to hit 35 mph today. Aerial photos of the fire show the plume of smoke has spread south to Carmel.

S.F. Chron

FoundingFatherDAR's diary

Update 1: CBS news is reporting the fire has grown to more than 2,000 acres. http://cbs5.com/...
Update 2: Thanks to SallyCat for posting these links Google map and local Monterey news
Additional data - CalFire page
Update 3: From KSBW news in Monterey (link above) -

Homeowners were ordered to evacuate from the Maymen Flat, Eureka Canyon Road, Summit Road and Ormsby Cut-Off Road area. {snip} close to Mount Madonna County Park and reportedly moving toward Corralitos.

By DailyKos