Quick Take:

San Jose gunman Samuel Cassidy “coordinated the destruction of his residence” with the mass shooting, sheriff’s officials say.

Wednesday’s mass shooting at a Valley Transit Authority rail yard in San Jose claimed the lives of nine people and left the community in shock.

Now authorities are sifting through the wreckage looking to understand why — and how — the gunman committed the horrific attack.

Evidence has painted a picture of the assailant, 57-year-old Samuel Cassidy, as a disgruntled VTA worker who hated his job.

And emerging reports Friday indicate that he may have been facing a disciplinary hearing at the agency where he worked as a maintenance worker for the last eight years.

Law enforcement sources said Cassidy faced a disciplinary proceeding after he made racial comments to co-workers. According to NBC News, he was scheduled to attend a hearing Wednesday, the day of the attack.

Representatives for VTA did not immediately respond to requests for comment.

Some who worked with Cassidy described him as a loner at the agency.

“Sam was definitely outside the group,” said Kirk Bertolet, 64, a 12-year VTA employee who was on duty at the time of the shooting. “I never once saw him sitting at a table with co-workers talking or doing anything. He was always beside himself doing something, and never interacted.”

Bertolet said the workplace was composed of blue-collar workers who were sometimes tough on each other.

“Sometimes, if you’re a little thin-skinned, maybe you don’t fit in,” he said.

The nature of the attack was deliberate, methodical and targeted, the investigation has revealed. Witnesses have said Cassidy appeared to pass over some people while selecting others.

“Based on recent developments in the investigation, we can say that the suspect has been a highly disgruntled VTA employee for many years, which may have contributed to why he targeted VTA employees,” Santa Clara County Sheriff’s Deputy Russell Davis said Thursday.

Several agencies, including the San Jose police and fire departments, the FBI and the Bureau of Alcohol Tobacco, Firearms and Explosives, were assisting the Santa Clara County Sheriff’s Office with the investigation at the crime scene and at Cassidy’s home on Angmar Court, where a fire ignited just minutes after the shooting began.

Santa Clara County Sheriff Laurie Smith has said he likely used a detonator device to ignite the fire at the same time as the shooting. The VTA rail yard is eight miles from his home.

FBI officials on Friday morning confirmed that investigators also found intact Molotov cocktails inside Cassidy’s home and that bomb technicians will be “working to make suspicious materials as safe as necessary so that investigators can continue to collect evidence.”

Erica Ray with the San Jose Fire Department said authorities have located devices at the home that they are going to render safe.

Ray could not elaborate on what would be done with the devices, but said people do not need to clear the area.

Steve Aponte with the San Jose Police Department said the bomb squad is “doing a final sweep today [of the house] to ensure they leave the property completely rendered safe.”

Explosive materials were also found in Cassidy’s locker at the VTA rail yard in the hours after the shooting.

Cassidy, who authorities said took his own life when deputies confronted him, was armed with three semiautomatic 9-millimeter handguns and 32 high-capacity magazines loaded with additional ammunition. Officials said he fired 39 shots.

Security video released by authorities showed Cassidy at the VTA rail yard walking calmly between the two buildings where the victims were shot Wednesday morning.

A VTA clerical worker, who wished to remain anonymous because she was advised not to speak to the media, said the first building houses the ways, power and signal team and the second building includes operations and light rail maintenance.

Based on the first building’s layout and exit locations, she said, the victims would have had “nowhere to go.”

“They didn’t deserve this,” she said through tears. “They were just good guys who loved their families, who just wanted to go to work and go home every day.”

At a vigil Thursday evening, hundreds of people mourned for the victims, who ranged in age from 29 to 63.

They have been identified as 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; and Alex Ward Fritch, 49.

Karman Singh recalled how his brother, Taptejdeep, 36, would joke that he looked younger than Singh, despite being six years older.

He often came to Taptejdeep for help, Singh said, describing how his brother “shielded me from responsibilities of this world.”

Whatever trouble he was in, “he was my first call,” Singh said.

Other families described similarly close relationships with the loved ones they lost.

Audrey, the daughter of Timothy Michael Romo, 49, said her dad would often call her his “favorite little girl,” to which she would playfully respond, “I’m your only little girl.”

Romo’s son, Scott, said that his father had been “everything I ever wanted to be as a man.”

“He was my superman, and I’ll never not miss him,” he said.

One victim, 49-year-old Alex Ward Fritch, died in a hospital after the attack. His wife, Terra Fritch, said she was by his side when died.

“We had one of those very special relationships that I think most people just dream of,” she told The Times. “We were never really apart. And if he was somewhere without me, it was definitely noticed. Like, where is the other half?”

The couple was supposed to renew their vows in Hawaii for their 20th wedding anniversary in September.

“Alex loved dirt bikes, tiki bars and “most of all, luckily, he loved me,” she said.

During the vigil, San Jose Mayor Sam Liccardo read the victims’ names, pausing a few seconds before each one. He spoke about how healing would be a long and hard journey for many.

“We’re here to share our pain, we’re here to share our love, to share our support for each other,” he said. “We’re here to express a singular message in our community: We will heal, and we will heal together.”

Victims’ support funds have been set up through Working Partnership USA and the Amalgamated Transit Union.

This story originally appeared in Los Angeles Times.