A California transit employee killed eight co-workers and wounded another before taking his own life on Wednesday in the latest of a spate of deadly mass U.S. shootings, prompting the state’s governor to ask: “What the hell is wrong with us?” Authorities did not immediately offer many details or a possible motive for the shooting, which unfolded about 6:30 a.m. Pacific Time (1330 GMT) at a light-rail yard for commuter trains of the Santa Clara Valley Transportation Authority (VTA). A bomb squad was searching the yard and adjacent buildings after at least one explosive device was found, Santa Clara County Sheriff"s Deputy Russell Davis said at a news conference. Sheriff Laurie Smith told reporters that gunfire was still going on when her first deputies arrived on the scene, and that the assailant took his own life, apparently when he became aware that police were closing in on him. She credited swift action by sheriff"s deputies, who rushed to the scene from their own headquarters next door to the rail yard, with preventing what might have been a much greater loss of life. Governor Gavin Newsom, appearing with Smith and others in San Jose, voiced exasperation at the frequency and regularity of gun violence in America. "There is a sameness to this and that numbness, I think, is something that we are all feeling," Newsom said. "It begs the damn question what the hell is going on in the United States of America. What the hell is wrong with us and when are we going to come to grips with this?" The gunman, the eight victims he shot dead, and a survivor who was hospitalized in critical condition were all employees of the transit agency situated near the city"s airport, officials said. Authorities did not give the gunman"s name or age. The San Jose Mercury News and other media outlets identified him as Samuel Cassidy, 57, a maintenance worker at the yard. Cassidy had worked for the transit authority since at least 2012, when he was listed as an "electro-mechanic," and was promoted to "substation maintainer" in 2015, according to records posted by the nonprofit website Transportation California. Last year, he earned a salary of $102,000, plus benefits and $20,000 in overtime, the records showed. Local television station KTVU-TV reported that Cassidy had been married for 10 years and divorced in 2009, citing an interview with his ex-wife, who reportedly told the station she had little contact with him over the past decade. Police stop a local resident leaving the area of the Santa Clara Valley Transportation Authority mass shooting suspects house that was set ablaze in San Jose, California, U.S. May 26, 2021. REUTERS/Peter DaSilva Police secure the scene of a mass shooting at a rail yard run by the Santa Clara Valley Transportation Authority in San Jose, California, U.S. May 26, 2021. REUTERS/Peter DaSilva Police secure the scene of a mass shooting at a rail yard run by the Santa Clara Valley Transportation Authority in San Jose, California, U.S. May 26, 2021. REUTERS/Peter DaSilva 1/6 Police secure the scene of a mass shooting at a rail yard run by the Santa Clara Valley Transportation Authority in San Jose, California, U.S. May 26, 2021. REUTERS/Peter DaSilva "ESSENTIAL WORKERS" "A horrible tragedy has happened today and our thoughts and love go out to the VTA family," Glenn Hendricks, chairman of the VTA board, told reporters. He said the shooting took place in a section of the rail yard where workers perform maintenance on vehicles, and was not in the facility"s operations and control center. San Jose, a city of about 1 million residents, lies at the heart of Silicon Valley, a global technology hub and home to some of America"s biggest high-tech companies. "These are, and were, essential workers," San Jose"s mayor, Sam Liccardo, said of the victims. He confirmed in television news interviews that authorities had also responded to a fire at the home of the suspect that erupted at about the same time as the shooting. Multiple fire department, police and bomb squad vehicles were still parked outside the suspect"s house, along a cul-de-sac in southeastern San Jose, hours after the shooting. An explosives-detecting robot sat in the street near the home while two bomb squad technicians entered the ranch-style house. Arson investigators along with agents of the FBI and U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives were also present. U.S. President Joe Biden was briefed on the shooting, and his staff continued to monitor the situation while keeping in close contact with local officials to offer any assistance needed, the White House said. "What"s clear, as the president has said, is that we are suffering from an epidemic of gun violence in this country, both from mass shootings and in the lives that are being taken in daily gun violence that doesn"t make national headlines," White House spokeswoman Karine Jean-Pierre told reporters. Mass gun violence, commonplace in a country with one of the highest rates of firearm ownership in the world, has escalated considerably following a year-long lull as the United States emerged from the worst of the COVID-19 pandemic this spring. Wednesday’s incident was the latest of at least eight deadly U.S. mass shootings in the past three months, including a string of attacks at Atlanta-area day spas in mid-March and a rampage days later that left 10 people dead at a Colorado supermarket. Last month, a former employee of an Indianapolis FedEx center shot eight workers to death and then took his own life.