Cal. Lab. Code § 3601
(a) Where the conditions of compensation set forth in Section 3600 concur, the right to recover such compensation, pursuant to the provisions of this division is, except as specifically provided in this section, the exclusive remedy for injury or death of an employee against any other employee of the employer acting within the scope of his or her employment, except that an employee, or his or her dependents in the event of his or her death, shall, in addition to the right to compensation against the employer, have a right to bring an action at law for damages against the other employee, as if this division did not apply, in either of the following cases: