Nine people were shot to death at a San Jose light rail yard on Wednesday morning, authorities said.
The suspect, an employee with the Santa Clara Valley Transportation Authority (VTA), was also dead from an apparent self-inflicted gunshot wound, according to Santa Clara County Sheriff's Office spokesperson Russell Davis.
Sources briefed on the investigation told ABC News that the suspect -- identified by authorities as Samuel Cassidy -- was armed with multiple weapons.
Multiple sources told ABC News the shooting is suspected workplace violence.
VTA employees were among those killed, according to Davis.
The Santa Clara County Office of the Medical Examiner-Coroner later identified the deceased victims 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.
Fritch died Wednesday night after being transported from the scene to a hospital in critical condition.
The deadly shooting occurred at around 6:30 a.m. PT at a VTA hub where maintenance is conducted and trains are stored. More than 40 employees were there at the time, according to the San Jose Police Department.
VTA employee Kirk Bertolet told ABC News he was working in the office next door to the light rail yard when he heard gunfire. He described it as a "surreal moment."
"I was hearing my coworkers calling the police and screaming," Bertolet recalled during an interview Thursday on "Good Morning America."
"We locked down in the secure room that my department was in and I notified our controllers and we stayed out of sight until we heard that the individual had moved from our building over to the next building," he added, "and then I left my office and went over there to see if I could render aid to anybody."
The Santa Clara County Sheriff's Office is adjacent to the VTA light rail yard, and the sheriff said that deputies ran from their desks toward the gunfire when they heard shots.
"I know that it saved many lives," Santa Clara County Sheriff Laurie Smith said at a press conference Wednesday.
Deputies did not exchange gunfire with the suspect, according to Davis.
After the shooting, a police dog detected a suspicious device and a bomb squad began working to clear each room in the facility, Davis said.
Craig Fair, special agent in charge of the Federal Bureau of Investigation's San Francisco field office, said it would take time to process the large crime scene.
A house fire that was noticed around the time of the shooting is believed to be linked to the suspect, sources told ABC News. The blaze is being investigated as a possible arson and federal evidence response teams were headed to both the house and the rail yard, sources said.
During a press conference Wednesday, local leaders noted that VTA employees are essential workers who went to work each day during the coronavirus pandemic.
Glenn Hendricks, chair of the VTA's board of directors, called the shooting a "horrible tragedy."
"We're so sorry this event happened," Hendricks said. "We will do everything we can to help people get through this."
San Jose Mayor Sam Liccardo told ABC News that he spoke with several employees who were at the facility during the shooting.
"There were concerns about this gunman, there’s no question," Liccardo said.
U.S. President Joe Biden and U.S. Attorney General Merrick Garland have both been briefed on the shooting.
Biden ordered flags to be lowered to half staff on Wednesday evening to honor the victims.
"There are at least eight families who will never be whole again," the president said in a statement. "There are children, parents and spouses who are waiting to hear whether someone they love is ever going to come home."
Biden remarked that the American flag has been lowered several times recently after similar shootings in Georgia, Colorado, South Carolina and Indiana.
"Every life that is taken by a bullet pierces the soul of our nation" he added. "We can, and we must, do more."
U.S. Vice President Kamala Harris described the shooting as "absolutely tragic."
"I have family that live in San Jose. I've worked for many, many years with the mayor of San Jose and that police department," Harris told reporters Wednesday. "My prayers and my thoughts are with all of those families that have been affected."
The VTA said service wasn't impacted by the shooting, but Hendricks said that light rail service is now suspended and likely will remain suspended for several days.
"We will have bus bridges in place to provide limited service while we work through this," the VTA wrote on Twitter Wednesday. "The light rail yard remains an active investigation scene, limiting our ability to provide service."
ABC News' Luke Barr, Jack Date, Justin Gomez, Jenna Harrison, Aaron Katersky, Josh Margolin, Alex Stone, Morgan Winsor and Haley Yamada contributed to this report.