The day after the Bay Area’s deadliest mass shooting rocked the region, authorities, community members and families of the victims remain shaken, searching for answers.

The shooting, which happened early Wednesday morning at a Valley Transportation Authority light rail yard, left a total of 10 people dead, including the shooter, making it the worst shooting in Bay Area history. In 1993, eight people and a gunman died in a skyscraper at 101 California Street in San Francisco.

As of Thursday morning, authorities had released the identities of all of the victims, revealed what kind of weapons the gunman had used and offered more insight on how the events unfolded. But what exactly led the shooter to open fire on his coworkers on a quiet spring morning is still unclear.

Here’s what we know so far, with updates coming as soon as we get them.

What happened?

Just after 6:30 a.m. Wednesday, a man identified as Samuel Cassidy opened fire upon coworkers in two separate buildings within a VTA Light Rail maintenance facility on Younger Avenue in San Jose. He then turned a gun on himself and took his own life as law enforcement officers closed in, authorities said.

Around the same time as the shooting broke out, a fire erupted at Cassidy’s San Jose home. Santa Clara County Sheriff Laurie Smith said Thursday that Cassidy is suspected of setting the fire before leaving his home Wednesday morning.

According to Smith, the massacre at the railyard was over within minutes as law enforcement officers from her office — one block from the rail yard — and San Jose police quickly arrived at the scene. Officers did not exchange gunfire with the suspect, she said. Soon after, bomb-sniffing dogs signaled to handlers that an explosive device may have been placed inside a VTA building, leading to a lockdown and search.

The VTA provides bus, light rail, and paratransit services and is a funding partner in regional rail service including Caltrain, Capital Corridor, and the Altamont Corridor Express. The shooting happened during the busiest time of day at the maintenance facility, when operators and maintenance workers are getting ready for the start of the day’s service, according to Raj Singh, the recording and financial secretary for Amalgamated Transit Union local 265, which represents VTA operators.

How many people were killed?

Throughout the day Wednesday, authorities had reported that a total of nine people had died in the shooting, including eight victims and the shooter. But by late Wednesday evening, the Santa Clara County Office of the Medical Examiner-Coroner confirmed that a ninth victim who had been in critical condition at a San Jose hospital had died of his injuries, bringing the death total to 10 and making this the deadliest mass shooting in Bay Area history.

Who are the victims? 

The Santa Clara County Office of the Medical Examiner-Coroner on Wednesday evening identified the nine deceased shooting victims as:

  • Paul Delacruz Megia, age 42
  • Taptejdeep Singh, age 36
  • Adrian Balleza, age 29
  • Jose Dejesus Hernandez III, age 35
  • Timothy Michael Romo, age 49
  • Michael Joseph Rudometkin, age 40
  • Abdolvahab Alaghmandan, age 63
  • Lars Kepler Lane, age 63
  • Alex Ward Fritch, age 43.

The ninth victim, Fritch, was initially taken to a hospital in critical condition but later died of his injuries.

All of the victims were employees of VTA, transit authorities confirmed Thursday morning.

“Today is a day to honor those individuals and their families and we want to support all of our employees who are grieving, as we are all grieving,” VTA Board Chair Glenn Hendricks said during a Thursday morning press briefing. “We know there is more information to come about this incident but today is about our employees and our families. It is about people.”

Who is the gunman?

The gunman has been identified as Samuel James Cassidy, 57, a longtime resident of San Jose. Cassidy had worked for the Valley Transportation Authority for about 20 years, initially as a mechanic and then more recently as a substation maintainer. Before joining the transit agency, he was employed as a mechanic at a San Jose Mazda dealership.

Although the FBI and local authorities continue to dig into his background, his ex-wife, neighbors and court records paint a picture of a man who often exhibited violent and aggressive behavior and had complained about being mistreated at work. In a 2009 court filing, an ex-girlfriend of his accused Cassidy of rape, sexual assault and “enraged” mood swings fueled by alcohol.

What kind of weapons were used?

Cassidy was armed with three semi-automatic handguns and 11 ammunition magazines each holding 12 rounds, making them high-capacity magazines that are illegal in California, according to Smith.

California’s Proposition 63, a ballot initiative passed by voters in November 2016, banned magazines holding more than 10 cartridges. Individuals who magazines with more than 10 cartridges were required to permanently alter them or dispose of them before July 1, 2017 by selling them to a licensed firearms dealer, transferring them to law enforcement, removing them from the state, or destroying them.

Security footage from a neighbor who lived across the street from Cassidy showed the suspect leaving his home at 5:39 a.m. in work attire and loading a large black duffel bag into his white Ford pickup truck.

Officers also found additional weapons and a large amount of ammunition inside of Cassidy’s home, sources told the Bay Area News Group.

Smith said explosive-sniffing dogs alerted authorities to his locker inside the VTA building on San Jose’s Younger Avenue, which contained “bombs, detonator cords, the precursors to an explosive.”

What was the motive?

As of Thursday morning, it remained unclear what led Cassidy to decide to go to his workplace and open fire on his coworkers.

It is also still unclear where Cassidy obtained his weapons, whether he was targeting certain individuals and how many explosives were discovered in VTA buildings, maintenance yards and his home.

Staff writers Robert Salonga, David DeBolt, Aldo Toledo and Fiona Kelliher contributed to this report.

Complete coverage of the VTA mass shooting.