This article is from the California Driving (and Surviving) FAQ, by "George J Wu" email@example.com with numerous contributions by others.
Yes. For felonies and public offenses (which include infractions and
misdemeanors) in the presence of the officer, or actions that could cause
great bodily harm or death, the sworn POST (Peace Officers Standard
Training) certified officer is empowered in the entire state [see Penal
Code 830, 832, 1523]. Furthermore, the authority of sheriffs, police
officers, etc., extends to any place in the state as to any public offense
committed (or believed to have been committed) within the political
subdivision which employs him or her [Penal Code 830.1].