▶ Watch Video: Extensive arsenal found at home of San Jose gunman

Multiple cans of gasoline, 12 firearms and approximately 22,000 rounds of various types of ammunition were found by law enforcement at the home of the gunman who fatally shot nine of his fellow employees at a light-rail yard in San Jose, California, local authorities announced Friday. Officials said that the suspect, Samuel Cassidy, 57, “was prepared to use his firearms to take as many lives as he possibly could.”

Santa Clara County Sheriff’s office

“It is clear that this was a planned event,” a statement from the Santa Clara County Sheriff’s office read. 

On Wednesday, the county sheriff’s office received multiple 911 calls about shots fired at the Santa Clara Valley Transportation Authority around 6:34 a.m. local time. Employees of the facility were evacuated from the building, which operates as a transit control center.

The gunman fired 39 shots and appeared to target some of the victims, employees of the Santa Clara Valley Transportation Authority, which operates the rail yard, Sheriff Laurie Smith told The Associated Press on Thursday. 

Deputies did not exchange gunfire with the suspect, who had two semi-automatic handguns and 11 magazines on him at the time. Investigators believe he died of a self-inflicted gunshot wound, said Deputy Russell Davis, a sheriff’s department spokesperson. 

At around the same time as the shooting, the San Jose Police Department and Fire Department responded to a fire at what was later determined to be Cassidy’s home. The sheriff said that he appeared to have set a timer or slow-burn device to set his home on fire. Officials believe that the suspect coordinated his home’s destruction. 

Santa Clara County Sheriff’s office

A bomb-sniffing dog initially detected explosive material at the crime scene, forcing officials to send a bomb squad to investigate “every crevice” of the facility, Davis said. Following the investigation at the rail yard, no explosives were found, officials reported Friday. 

Cassidy was described by his fellow coworkers at VTA as “disgruntled,” the sheriff’s office said. His ex-wife, Cecilia Nelms, told CBS News that he struggled with a temper. “That was one of our biggest problems. He was very quiet, keep things to himself,” Nelms said.

The investigation is still ongoing. Officials are still determining a motive.