The department tweeted a photo of Deputy Nicholas O'Loughlin.
"It is with deep sadness that we report the sudden & tragic death of Deputy Nicholas O'Loughlin. Nicholas was killed in an off-duty traffic collision early this morning," the posted stated, adding that he is survived by by his father, mother and brother.
The time, location and circumstances of the crash were not immediately released. Chino police were handling the investigation.
Sheriff's officials confirmed a suspect identified as Yijie Mao was arrested for driving under the influence.