The incident occurred just before 1 a.m. in the 14700 block of Firestone Boulevard and Trojan Way in La Mirada, the sheriff's headquarters bureau told KTLA-TV, Los Angeles.
The man was taken to a nearby hospital, where he was pronounced dead. The sheriff's department is investigating the killing and hasn't released information on what led to it.
"Whenever an officer-involved shooting occurs involving Los Angeles County sheriff's deputies, and it results in a fatality, multiple independent investigations immediately begin at the scene," the headquarters bureau said in a statement.
The Los Angeles County district attorney and coroner, as well as the sheriff's homicide and internal affairs bureaus, will investigate. Attorneys with the Los Angeles Office of Independent Review also responded to the scene.