New reports have revealed that the shooter may have targeted the victims, who ranged in age from 29 to 63. They were found in two buildings at the Valley Transit Authority on Wednesday.
"It appears to us at this point that he said to one of the people there: "I'm not going to shoot you,'" Santa Clara Sheriff Laurie Smith told the Associated Press on Thursday. "And then he shot other people. So I imagine there was some kind of thought on who he wanted to shoot."
One witness said the shooter "had a list of people that he was going to kill yesterday."
"He shot some people, he let another person live, and then he went around and shot everybody again," said Kirk Bertolet, 64, who has worked for the VTA for 12 years and was on duty during the shooting Wednesday.
Bertolet said the gunman, who has been identified as Samuel Cassidy, 57, then "cooly waked by some people coming out of the other building ... then he walked in that building and found his targets over there. He killed the people he wanted to kill."
Smith told the "Today" show that Cassidy, who had been employed at the VTA for at least eight years, was "very deliberate, very fast" during the shooting rampage.
Officials initially said he was found with two semiautomatic handguns and 32 loaded magazines, but later updated that number to three guns. Smith told the AP that he fired 39 shots and that the 9mm handguns he had appeared to be legal, although the high-capacity magazines, which hold 12 rounds, are illegal in California.
Cassidy's ex-wife, Cecilia Nelms, said he had talked about killing people at work more than a decade ago.