Police say a retired administrator at Cal State Fullerton was stabbed to death in a campus parking lot on Monday as students at the university returned for the first day of fall classes.

Police responded at 8:30 a.m. on Monday to a stabbing in a campus parking lot. The suspect remained at large until Wednesday evening, when Police Chief Robert Dunn says Fullerton detectives arrested Chuyen Vo, 51, at his Huntington Beach residence on Wednesday.

"Fullerton police detectives believe based on their investigation that Vo acted alone during the planning and commission of this murder," Dunn told reporters. "We now know that Vo and Chan were co-workers."

Please avoid the area of the 600 Blk of Langsdorf due to police activity. A homicide occurred on the campus of @csuf and the FPD will be handing the investigation due to an MOU with @csufpd . FPD PIO will be handling all media inquiries and he is en route to the scene. pic.twitter.com/K8dLLGHJYo — FullertonPD PIO (@FPDPIO) August 19, 2019

UPDATE, 10:25 AM: Crime appears to be a homicide caused by a bladed weapon. Was reported at about 8:30 this morning 8/19/19 in the parking lot South of College Park building. Suspect description: male with black hair, black pants and black shirt. https://t.co/b97XF25JAe — Cal State Fullerton (@csuf) August 19, 2019

CAMPUS UPDATE 12:25 PM: The victim involved was in his late 50s, and was a retired administrator working as a consultant on campus. Previous reports incorrectly indicate he was a faculty member. — Cal State Fullerton (@csuf) August 19, 2019

Officers identified the victim as Steven Shek Keung Chan, a 57-year-old from Hacienda Heights, Calif. Chan worked as an administrator on the campus before retiring. He had recently been hired to work as a university consultant.

The stabbing happened as police on campus were in the middle of filming active shooter scenes for an emergency response training video to be used by staff, faculty and students.

—Updated at 5:05 p.m. August 22, 2019