Investigators arrested James E. Milliken on suspicion of murder, according to a note from college president Bill Scroggins.
The Los Angeles County Sheriff's Department confirmed Milliken's arrest for murder and said he remains in custody but did not provide further details.
Milliken is suspected of intentionally running over Rafael "Ralph" Barragan Jr., a 63-year-old driver who transported students with disabilities for the school's ACCESS program. Barragan had worked for the campus since July 2007.
Milliken was described as a former employee of the college who also worked as a driver for the ACCESS program from October 2016 until he resigned in September 2021.
"Losing Ralph has been heartbreaking for our campus community," Scroggins wrote. "The circumstances of his passing are additionally painful."
No additional details on the motive for the alleged killing have been released at this time.
Barragan started working at the school after a 23-year career as a bus driver for the Metropolitan Transportation Authority.
"Ralph was highly visible on campus, gracious, popular and respected."
Barragan died on campus Thursday morning after Los Angeles County deputies arrived to find him unresponsive and suffering from trauma.
Employee struck, killed in apparently 'intentional act' at Mt. San Antonio College in Walnut: LASD
The driver accused of hitting Barragan was treated for his injuries at a local hospital and was detained by authorities.
Anyone with additional information about the incident is to call the sheriff's Homicide Bureau at (323) 890-5500.