Authorities said Wednesday that a shooting at a rail yard in San Jose, California, killed ten people, including the gunman, and injured others. Many details remained a mystery. According to Deputy Russell Davis, a spokesman for the Santa Clara County Sheriff’s Office, the investigation is centered on 101 West Younger Avenue, which houses the Santa Clara Valley Transportation Authority’s maintenance and dispatch center.

According to Deputy Davis, the police began receiving 911 calls around 6:34 a.m. local time. Deputies arrived at the hub and discovered “multiple victims who were shot at the scene,” he said. Later, he told reporters that eight people had been killed. Late Wednesday, officials announced the death of a ninth victim at a nearby hospital.

Employees of the V.T.A. were among the victims, he claimed. According to Deputy Davis, the gunman was also killed. Officials said he appeared to have committed suicide. The gunman was identified as Samuel James Cassidy, 57, a maintenance worker with the V.T.A. for at least a decade, by senior California law enforcement officials. Deputy Davis stated that he had no idea what type of weapon was used or what the possible motive was. He also stated that bomb squad teams were working to secure the area. Mayor Sam Liccardo of San Jose said in an interview that “at least several people” were killed in the shooting. He said the facility had been evacuated.

“It appears that the suspect’s house is on fire but that there was nobody inside,” Mr. Liccardo said. “There’s a strange connection here between arson and the shooting.” Gov. Gavin Newsom of California said the shooting raised stark questions for the country. “What the hell is wrong with us, and when are we going to realize it?” he asked. ” Glenn Hendricks, chairman of the V.T.A. board of directors, told reporters on Wednesday that the shooting occurred in the facility’s yard, not “the operations control center.”

He described the location as a maintenance yard from which V.T.A. vehicles are serviced and dispatched. He also stated that the V.T.A. would halt light rail service on Wednesday. “It’s a terrible tragedy,” he said. “I have no information about the investigation or what happened,” said Brandi Childress, a V.T.A. spokeswoman. Employees were on the job at the time of the shooting, she added.

“It is where our dispatchers and maintenance are,” she explained. “They get up early and show up. As a result, the emphasis is on containing and evacuating employees. All of our trains are stored and maintained there.” Mr. Cassidy was described as frightening those around him.

Mayor Liccardo stated that coworkers had “generalized concerns about his mental health.” Connie Wang, 58, the suspect’s former girlfriend, said she hadn’t seen or spoken to him in 12 years but described him as “not mentally stable.”

Mr. Cassidy’s neighbor, Doug Suh, a real estate agent who lives across the street in a suburban neighborhood of cul-de-sacs and palm trees, described him as short-tempered. “I was terrified of him,” Mr. Suh admitted. “My wife was also terrified of him.” According to family court records, Mr. Cassidy was married for ten years before divorcing in 2004. The couple did not have any children.

Mr. Suh stated, “He lived alone.” “I didn’t see any of my friends or family. “I never saw anyone else enter the house.”

On Wednesday night, the medical examiner’s office in Santa Clara County identified eight of the victims and later announced the death of a ninth at the Santa Clara Valley Medical Center. Their ages ranged from 29 to 63.

Christina Gonzalez, Mr. Rudometkin’s cousin, had rushed to a Red Cross center earlier on Wednesday, where relatives of transportation authority employees were told to wait for news. She stated that Mr. Rudometkin had attended a union meeting earlier in the day. Her cousin was “very proud, loved his job, and just always stood up for everyone’s rights,” she said.