A gunman who killed nine people at a California rail yard where he worked appeared to target some of the victims, a sheriff told The Associated Press, while a Biden administration official said the shooter spoke of hating his workplace when customs officers detained him after a 2016 trip to the Philippines.
Samuel Cassidy, 57, arrived at the light rail facility for the Valley Transportation Authority in San Jose about 6am on Wednesday with a duffel bag filled with semi-automatic handguns and high-capacity magazines, Santa Clara County Sheriff Laurie Smith said on Thursday.
"It appears to us at this point that he said to one of the people there: 'I'm not going to shoot you,"' Smith said.
"And then he shot other people. So I imagine there was some kind of thought on who he wanted to shoot."
Cassidy, who fired a total of 39 bullets, killed himself as deputies closed in on the facility serving the county of more than one million people in the heart of Silicon Valley. More than 100 people were there at the time, and authorities found five victims in one building and two in another, Smith said.
Sheriff's officials described Cassidy as "a highly disgruntled VTA employee for many years," saying that may have contributed to him targeting the workers. Documents show he had worked at the transit authority since at least 2012.
After being detained by customs officers in 2016, Cassidy was found to have a memo book with notes on how he hated the Valley Transportation Authority, according to a Biden administration official who described a Department of Homeland Security memo laying out Cassidy's statements. The official saw the memo and detailed its contents to the AP but was not authorised to speak publicly about the ongoing investigation.
The Wall Street Journal first reported the memo.
Cassidy's ex-wife said he had talked about killing people at work more than a decade ago.
"I never believed him, and it never happened. Until now," a tearful Cecilia Nelms told the AP on Wednesday.
She said he used to come home from work resentful and angry over what he perceived as unfair assignments.
"He could dwell on things," she said.
The two were married for about 10 years until a 2005 divorce filing, and she had not been in touch with Cassidy for about 13 years, Nelms said.
Sheriff's officials said the three 9 mm handguns Cassidy brought to the rail yard appear to be legal. Authorities do not yet know how he obtained them.
He also had 32 high-capacity magazines, some with 12 rounds. In California, it is illegal to buy magazines that hold more than 10 rounds. However, if Cassidy obtained them before Jan. 1, 2000, he would have been allowed to have them unless he was otherwise prohibited from possessing firearms.
The sheriff said authorities found explosives at the gunman's home, where investigators believe he had set a timer or slow-burn device so that a fire would occur at the same time as the shooting. Flames were reported minutes after the first 911 calls came in from the rail facility.
The attack was the 15th mass killing in the US this year, all shootings that claimed at least four lives each for a total of 87 deaths, according to a database compiled by The Associated Press, USA Today and Northeastern University.
President Joe Biden urged Congress to act on legislation to curb gun violence, saying, "Every life that is taken by a bullet pierces the soul of our nation. We can, and we must, do more."
Several long-time employees were killed, many of whom worked together.
The victims were Alex Ward Fritch, 49; Paul Delacruz Megia, 42; Taptejdeep Singh, 36; Adrian Balleza, 29; Jose Dejesus Hernandez, 35; Timothy Michael Romo, 49; Michael Joseph Rudometkin, 40; Abdolvahab Alaghmandan, 63; and Lars Kepler Lane, 63.