SAN JOSE, Calif. - Police and federal investigators sought on Thursday to determine why a Northern California transit employee opened fire on his co-workers, killing nine people in the latest mass shooting to haunt the United States.
The accused gunman shot himself as police closed in on him, minutes after gunfire erupted at about 6:30 a.m. Pacific time at a light rail yard in the heart of Silicon Valley, according to Santa Clara County Sheriff Laurie Smith.
Police did not publicly name the gunman. The San Jose Mercury News and other news media identified him as Samuel Cassidy, 57, a maintenance worker at the yard.
Firefighters responded to a fire at a home where the suspect lived at about the same time that the shooting was first reported. A police bomb squad searched the rail yard and adjacent buildings after an explosive device was found.
Police declined to speculate on a motive for the shooting rampage, saying that their work at the scene could take several days, assisted by the Federal Bureau of Investigation and Bureau of Alcohol, Tobacco, Firearms.
California Governor Gavin Newsom said at a Wednesday afternoon news conference that the massacre was a symptom of a larger American problem.
"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?" Newsom said.
A White House spokeswoman told reporters that the shooting was further evidence that the United States was in the grip of an "epidemic of gun violence."
LATEST MASS SHOOTING
The gunman and the nine victims shot dead were all employees of the transit agency situated near the city's airport. The victims were found in two buildings on the site.
The County of Santa Clara medical examiner-coroner's office identified the victims late on Wednesday. They appeared to all be men and ranged in age between 29 and 63. Their names are: Paul Delacruz Megia, Taptejdeep Singh, Adrian Balleza, Jose Dejesus Hernandez III, Timothy Michael Romo, Michael Joseph Rudometkin, Abdolvahab Alaghmandan and Lars Kepler Lane.
The ninth victim, Alex Ward Fritch, 49, died late Wednesday after he was taken to the hospital in critical condition, the medical examiner's office said, according to NBC Bay Area.
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.
The suspect and another individual filed domestic violence restraining orders against one another in 2009, three years after Cassidy and his wife divorced, according court records showed.
San Jose is a city of about 1 million people in Silicon Valley, a global technology hub and home to some of America's biggest tech companies.
Wednesday's incident was the latest of at least nine 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 killed 10 at a Colorado supermarket.
Last month, a former employee of an Indianapolis FedEx center shot eight workers to death before taking his own life. Earlier this month a man fatally shot his girlfriend and five other people before taking his own life at a birthday party in Colorado.