An employee fatally shot nine people at a California train yard before turning the gun on himself as police closed in.
The shooting took place at the Santa Clara Valley Transportation Authority (VTA) site in San Jose.
The victims, named early on Thursday, include transit employees. No motive for the attack has been established.
It was the California Bay area’s deadliest mass shooting since 1993, when eight people and a gunman died in a San Francisco skyscraper.
Across the US, there have been 231 mass shootings so far this year, according to the Gun Violence Archive. A mass shooting is defined by the group as a crime in which four or more people are fatally shot.
Law enforcement officials told CBS News, the BBC’s partner in the US, that the suspected gunman in this latest incident was 57-year-old Samuel Cassidy.
At a press conference on Thursday, VTA staff spoke about the victims, and the loss felt by VTA “family”.
“Some of us get training on what to do when there is an active shooter event – but not about the aftermath,” said acting VTA CEO Evelynn Tran.
“I saw the immense pain of the families and I saw their faces when they got the news,” she said. “I felt immensely helpless.”
Who are the victims?
- Paul Delacruz Megia, 42
- Taptejdeep Singh, 36
- Adrian Balleza, 29
- Jose Dejesus Hernandez III, 35
- Timothy Michael Romo, 49
- Michael Joseph Rudometkin, 40
- Abdolvahab Alaghmandan, 63
- Lars Kepler Lane, 63
- Alex Ward Fritch, 49
Eight victims were initially reported dead on Wednesday afternoon. Mr Fritch, who had been taken to Santa Clara Valley Medical Center in critical condition, died late on Wednesday bringing the total killed to nine.
Shots were first fired at around 06:30 local time (14:45 GMT) on Wednesday in the VTA light rail yard. According to a local CBS station, the attack unfolded during an employee meeting.
A spokesperson for Santa Clara County Sheriff’s office told CBS said the shooter was still firing rounds when officers arrived at the scene. They added that sheriffs did not exchange gunfire with the gunman, and it is believed he took his own life as officers closed in on him.
Among the victims was Taptejdeep Singh, a light rail operator for the VTA. His cousin, Batta Singh, told the New York Times that Mr Singh was a gregarious man and the kindest person in his family.
Mr Singh had a wife and two young children, his cousin told the newspaper. Family members said that officials told them that Mr Singh tried to save his colleagues when the shooting began, calling out to alert his co-workers and ushering a woman into a secure room, the Times reported.
Michael Rudometkin was a VTA union member, his family told the Washington Post. He was a “wonderful son, brother, loving husband, uncle, cousin and friend to many”, his mother, Rose Rudometkin, said to the newspaper.
Paul Peralez, who identified himself as a friend of “Mikey”, posted a photo of him on Facebook, writing that he and his father had been planning a golf day with him.
“Now that will never happen again,” Mr Peralez wrote. “My family and I have lost a long time great friend and there are no words to describe the heartache we are feeling right now, especially for his family.”
Authorities searched the VTA facility after a bomb-sniffing dog detected possible explosives at the site, though none were found.
Jeff Rosen, the county’s district attorney, said the shooter used “multiple guns” – all of which had been registered.
Cassidy’s ex-wife, Cecilia Nelms, told the Associated Press news agency that he told her he wanted to kill his colleagues, but she had never believed he would do it.
Doug Suh, a neighbour of Cassidy, told the Mercury News the gunman was “lonely” and “strange”.
Just before the shooting, a fire broke out at a home belonging to Cassidy, according to local media. Authorities say they are looking into whether the suspect may have set his home on fire.
Santa Clara is the largest county in California’s Bay Area and is home to Silicon Valley, America’s technology industry hub. It encompasses several cities in Northern California including Cupertino, San Jose and Mountain View.
The Santa Clara VTA operates three train lines, making up over 40 miles (65km) of rail. It also runs dozens of bus lines.
“These folks were heroes during Covid-19… The VTA never stopped running,” said Santa Clara County Supervisor Cindy Chavez, according to CBS. “They just kept at work, and now we’re calling on them to be heroes a second time to survive such a terrible, terrible tragedy.”
Speaking from near the crime scene, Governor Gavin Newsom condemned the “rinse and repeat” cycle of US mass shootings.
“What the hell is wrong with the United States of America?” the Democrat said. “When will we put down our arms?”
President Joe Biden called the attack a “horrific tragedy” and ordered flags to be flown at half mast as he again urged Congress to take action on gun control.
“Every life that is taken by a bullet pierces the soul of our nation,” he said. “We can and we must do more.”