BONNY DOON, Calif. -- About 1,500 residents in the heavily forested hills north of Santa Cruz are being told to leave their homes as a quick-moving wildfire spreads through the area.

The California Department of Forestry and Fire Protection said the 300-acre blaze broke out in the Bonny Doon area of Santa Cruz County just before 3 p.m. Wednesday.

Fire officials said they expect the fire to grow to as many as 1,000 acres.

Fire officials said more than 1,000 homes are threatened by the fire.

Battalion Chief Paul Van Gerwen said there have been 500 mandatory evacuations and 1,000 voluntary evacuations.

The Red Cross has set up a shelter at San Lorenzo Valley Middle School, KSBW-TV in Monterey reported.

Julie Haff, superintendent of San Lorenzo Valley Unified School District, said the cafeteria, gymnasium and administrative offices have been left open for residents fleeing the area.

"The size has grown considerably," Haff said. "The smoke covers the entire length of the football field at the high school."

Santa Cruz Animal Services workers are available to assist in evacuating livestock and domesticated animals.

More than 175 firefighters are working to battle the blaze.

Fire officials said seven airtankers and more than 30 fire engines were at the blaze trying to defend nearby homes.

This is the second major wildfire in Santa Cruz County in less than three weeks.

The Summit Fire destroyed more than 30 homes and scorched more than 4,200 acres along Summit Road near Mt. Madonna over Memorial Day weekend.