Washington Revised Code Title 9A. Washington Criminal Code § 9A.84.020. Failure to disperse

(a) He or she congregates with a group of three or more other persons and there are acts of conduct within that group which create a substantial risk of causing injury to any person, or substantial harm to property; and

(b) He or she refuses or fails to disperse when ordered to do so by a peace officer or other public servant engaged in enforcing or executing the law.