The public is being advised to avoid the area.
WATCH: SKY7 video of Alameda County Fire Department crews battling a fire at the historic Lorenzo Theater in San Lorenzo
Crews battle fire at historic Lorenzo Theater in San Lorenzo
The 73-year-old theater closed in 1982, according to Cinema Treasures, and the nonprofit organization Lorenzo Theater Foundation was formed in 1999 to work for its preservation and restoration.
The theater was designated as a California Historic Resource in 2001, according to Cinema Treasures.