An employee opened fire Wednesday at a California rail yard serving Silicon Valley, killing eight people before ending his own life, authorities said.

The suspect was an employee of the Valley Transportation Authority, which provides bus, light rail and other transit services throughout Santa Clara County, the largest county in the Bay Area, authorities said.

The attacker was identified as 57-year-old Sam Cassidy, according to two law enforcement officials. Investigators offered no immediate word on a possible motive.

The shooting took place around 6:30 a.m. at a light rail facility that includes a transit-control center, parking for trains and a maintenance yard.

Sheriff’s spokesman Deputy Russell Davis said the attack also resulted in “multiple major injuries.” He did not know the type of weapon used. He said the victims included VTA employees. Authorities did not release any of the victims’ names.

“These folks were heroes during COVID-19. The buses never stopped running, VTA didn’t stop running. They just kept at work, and now we’re really calling on them to be heroes a second time to survive such a terrible, terrible tragedy,” Santa Clara County Supervisor Cindy Chavez.

Santa Clara County District Attorney Jeff Rosen said it was his understanding the shooting happened inside the VTA building.

Victims’ grief-stricken families sat huddled together, holding hands and crying, after learning they had lost a loved one, Rosen told reporters, describing the scene inside a county building.

“They’re just sitting and holding hands and crying,” Rosen said. “It’s terrible. It’s awful. It’s raw. People are learning they lost their husband, their son, their brother.” He said about 100 people were inside the family reunification center.

Police vehicles and orange crime-scene tape blocked off the area, and reporters were kept at a distance The rail yard is in the city’s administrative neighborhood, near the sheriff’s office and city and county offices.

Bomb squads were searching the rail complex after receiving information about possible explosive devices inside the building, Davis said.

Officials were also investigating a house fire that broke out shortly before the shooting, Davis said. Public records show Cassidy owned a two-story home where firefighters responded Wednesday morning.

VTA trains were already out on morning runs when the shooting occurred. Light rail service was to be suspended at noon and replaced with bus bridges, agency Chairman Glenn Hendricks told a news conference.

“It’s just very difficult for everyone to be able try to wrap their heads around and understand what has happened,” Hendricks said.

Outside the scene, Michael Hawkins told The Mercury News that he was waiting for his mother, Rochelle Hawkins, who had called him from a co-worker’s phone to assure him that she was safe.

When the shooting started, “she got down with the rest of her coworkers” and dropped her cellphone, Michael Hawkins told the newspaper. Rochelle Hawkins did not see the shooter, and she was not sure how close she had been to the attacker, her son said.

San Jose, the 10th-largest city in the U.S. with more than a million people, is about 50 miles south of San Francisco in the heart of Silicon Valley.

In the city itself, the most recent mass shooting occurred in 2019 at a private home, according to The Mercury News, in what police said was a quadruple murder and suicide precipitated by family conflict.

Wednesday’s attack was the county’s second shooting in less than two years. A gunman killed three people before killing himself at a popular garlic festival in Gilroy in July 2019.

At a news conference, San Jose Mayor Sam Liccardo lamented the “horrific day for our city.” Gov. Gavin Newsom said in a tweet that his office was “in close contact with local law enforcement and monitoring this situation closely.”

Agents from the FBI and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives were responding to the crime scene, officials said.