(KRON) -- A Valley Transportation Authority (VTA) employee, who is accused of shooting and killing his coworker on Friday in San Jose, was arrested, the Santa Clara County Sheriff's Office (SCCSO) said in a press release. Duc Minh Bui, 33, was arrested Sunday around 12:14 p.m. near his San Jose residence. The shooting was an isolated incident, and Bui was "solely responsible" for the victim's death, according to SCCSO. Bui and the victim both worked at VTA. Authorities are still working to determine a motive in the shooting. ‘Welcome to Antioch’: Business owner calls city the new Oakland after violent weekend Duc Minh Bui, 33, was arrested on Sunday for fatally shooting a VTA coworker on Friday, Sept. 20, authorities said. (Santa Clara County Office of the Sheriff) The shooting happened around 9:53 p.m. on Sept. 20 when deputies responded to the VTA Chaboya Division Yard on South 7th Street in San Jose. The victim, an unidentified man, suffered at least one gunshot wound and died at the scene. On Friday, VTA said it is "committed to supporting its employees during this difficult time, and mental health professionals have been made available to employees and their families.” Bui was booked into the Santa Clara County Main Jail on a first-degree murder charge. The Santa Clara County Medical Examiner-Coroner's Office has been notified about the fatality. The victim's identity will be released at a later time. SCCSO says anyone with information on this "around-the-clock investigation" is asked to call its office at 408-808-4500. Anonymous tips can be sent by contacting 408-808-4431. Three years ago, a mass shooting at a VTA rail yard killed nine people. The shooter was identified as a VTA employee.