Dramatic four-minute body cam video released by Sheriff’s Office shows deputies arriving at mass shooting scene.

“Based on recent developments in the investigation we can say that the suspect has been a highly disgruntled VTA employee for many years, which may have contributed to why he targeted VTA employees.” -- Sgt. Russell Davis of the Santa Clara County Sheriff’s Office.

The man identified by California law enforcement officials as the gunman in a mass shooting at a San Jose rail yard on Wednesday lived alone and had a hostile personality, according to interviews with a neighbor and an ex-girlfriend, as well as a review of court records. The gunman, Samuel James Cassidy, 57, lived southeast of downtown San Jose, in a suburban neighborhood of cul-de-sacs and palm trees, public records show. Doug Suh, a real estate agent who lived across the street, described Cassidy, who authorities say appeared to have killed himself, as someone with a short temper.

Alex Ward Fritch, 49, who had been in critical condition since being taken to Santa Clara Valley Medical Center Wednesday morning, died from his injuries, the County of Santa Clara Medical Examiner/Coroner. said.

Investigators were seeking a motive for the morning attack by a Santa Clara VTA transit supervisor on his co-workers, leaving eight dead and seriously injuring at least one other.