A dozen guns, roughly 25,000 rounds of ammunition, suspected Molotov cocktails and multiple cans of gasoline were found inside the San Jose mass shooting suspect's home, the Santa Clara County Sheriff's Office said Friday.
The gunman, 57-year-old Samuel Cassidy, was a VTA employee described by co-workers as being "disgruntled." He turned the gun on himself after Wednesday morning's rampage at a VTA yard rail that left nine other VTA employees dead.
"Based on current evidence obtained by Sheriff’s Office Detectives at the VTA yard and the suspect’s residence, it is clear that this was a planned event and the suspect was prepared to use his firearms to take as many lives as he possibly could had Sheriff’s Deputies not made entry to stop his rampage," the sheriff's office said in a statement.
Authorities also discovered "potential explosive precursor materials" at Cassidy's home and the VTA rail yard, the sheriff's office said. Bomb squad personnel scoured the rail yard and didn't find any explosives.
Sheriff Detective Sergeant Joseph Piazza said weapons were deliberately placed throughout the home.
"Based on my experience, I would think that weapons would be stored in different locations and placed there to access them in a time of emergency," Piazza said. "If he was contacted by someone or law enforcement, he would have access to those weapons in various areas of the house."
Friday's search of the house also seemed to solve a mystery of how a fire at the home ignited about the same time Cassidy is seen on the VTA grounds Wednesday morning just before the shooting started.
Detectives said Cassidy filled a pot on a lit stove with ammunition and surrounded by accelerants.
"So it is likely that the ammunition in that pot would have heated to a point where the powders inside would have detonated and likely ignited the accelerants," Piazza said.
The search at the home was scheduled to wrap up on Friday, but digital search warrants are also being worked on to look at electronic evidence, including surveillance video and computer data.
The shooter's father, James Cassidy, spoke to the Mercury News on Friday.
He told the newspaper that his son was bipolar but the violence was unexpected. Cassidy also apologized to the victims' families.
"I don’t think anything I could say could ease their grief. I’m really, really, very sorry about that," he told the newspaper.