
A Rancho Cucamonga man became unresponsive during a traffic stop that involved a use of force in Claremont on Friday afternoon, Nov. 28, and was later pronounced dead.
Claremont police had pulled over Diego Alfonso Rios, whose age was not available, on suspicion of driving under the influence, police said in a statement on Saturday.
Police at 3:18 p.m. Friday received two reports of a male acting erratically in the area of Claremont Boulevard and Andrew Drive. When officers arrived in the area, they observed Rios driving and conducted a traffic enforcement stop. When the officers asked Rios to step out of the vehicle, a use-of-force incident occurred, Claremont police Lt. Mark Hamill said in the statement.
Police on Saturday declined comment when asked what type of use of force was used.
Rios became unresponsive and officers started lifesaving measures until paramedics from the Los Angeles County Fire Department arrived and continued emergency medical treatment. Rios was then transported by ambulance to Pomona Valley Hospital Medical Center, where he was later pronounced dead.
The Los Angeles County medical examiner will determine the cause of death. The Los Angeles County Sheriff’s Department homicide bureau is investigating the case and the Los Angeles County district attorney’s office Justice System Integrity Division is monitoring the investigation.
Anyone with information about the case can call 323-890-5500 or submit anonymous tips by calling Crime Stoppers at 800-222-8477.

