SAN FRANCISCO — Silicon Valley stalwart Cooley opened an office in Los Angeles to serve clients in Southern California’s burgeoning tech community, as well as established media companies, the firm announced Tuesday.

Four partners are setting up shop in Santa Monica, including David Hernand, former co-chair of Gibson, Dunn & Crutcher’s media, entertainment and technology practice; corporate and venture capital attorneys David Young and C. Christopher Shoff, formerly with DLA Piper; and Jennifer Massey, formerly with the entertainment law firm of Morris Yorn Barnes Levine Krintzman Rubenstein & Kohner.