Deputy Lawrence "Larry" Falce, 70, was assaulted after being involved in a collision in his personal vehicle on New Year's Eve, the sheriff's department said.
The incident happened around 10:50 a.m. Sunday at the intersection of Kendall Drive and University Parkway.
Officials say Falce was involved in a collision with another person. After the two drivers made contact with each other, the driver of the other vehicle allegedly struck Falce, causing severe injuries, the sheriff's department said.
Falce was hospitalized and died Tuesday.
The suspect involved in the fight was taken into custody. The suspect's identity has not been released.
Falce had been with the department for 36 years, and worked patrol at Central Station for the past 32 years. Before joining the department, he served in the U.S. Army.
"Larry was loved by his peers and the community members he served. More importantly, he cared about so many people he called family," the sheriff's department said. "Larry is survived by his sister, Marjorie, and his girlfriend of many years, Deborah. He also leaves behind many extended loved ones."
A procession to honor the deputy and accompany his body from Loma Linda Hospital to the coroner's office was held at 10 p.m.
Fellow deputies made a line from the hospital to the coroner's van and stood solemnly as Falce's body was wheeled out in a coffin draped with the American flag.
The procession moved slowly through surface streets to the San Bernardino County coroner's office.
The Sheriff's Employees Benefits Association stated on Facebook that it would pay for Falce's funeral.