The man who killed nine people in California this week had 12 firearms, more than 20 cans of petrol, and approximately 22,000 rounds of ammunition at his house, police say.
Samuel Cassidy, an employee at the Santa Clara Valley Transportation Authority (VTA) site in San Jose, opened fire at the site on Wednesday.
He killed himself as police closed in, officers said.
The mass shooting was the California Bay area’s deadliest since 1993.
So far this year, the US has recorded 233 mass shootings, the Gun Violence Archive reports.
According to the local sheriff’s office, this was “a planned event and the suspect was prepared to use his firearms to take as many lives as he possibly could”.
Police announced on Friday that the gunman had also set his home on fire before the attack.
Guns were hidden in crawl spaces and doorways, a spokesman told reporters at a press conference. The home was “very cluttered”, he said.
Officers also said Cassidy had put bullets in a cooking pot on the stove, which detonated and set the house on fire. An FBI agent quoted by Reuters news agency said this blaze probably destroyed evidence which could have helped provide a motive for the shooting.
Who were 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
Emergency services were responding to reports of a fire at what was later found to be Cassidy’s home at the same time as police were heading to the scene of the shooting.
Shots were first fired at around 06:30 local time (14:45 GMT) on Wednesday at the VTA site in San Jose.
Officers said Cassidy was armed with three semi-automatic hand guns when he opened fire after a morning union meeting.
Sheriff Laurie Smith added on Friday that Cassidy’s locker at the rail yard had “materials for bombs, detonator cords, the precursors to an explosive”.
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 that he was “lonely” and “strange”.