Nine people including the suspected gunman are dead after a transit worker opened fire on colleagues at a rail yard in San Jose, California, on Wednesday.
Authorities say the lone suspect, Samuel Cassidy, took his own life at the scene.
What are the details?
NBC News reported that calls of shots fired began around 6:30 a.m. at Santa Clara Valley Transportation Authorities facility, and law enforcement rushed to respond.
"When the shots were still being fired, our teams, with San Jose PD, are entering the building while shots were still going off," Santa Clara County Sheriff Laurie Smith told reporters. "We attempted rescues. We have some very brave officers and deputies."
Sources told ABC News that Cassidy, a VTA employee, had multiple weapons with him in the massacre, and is believed to have taken his own life after murdering eight people. Multiple VTA employees were among the victims, and one survivor is in critical condition.
The Washington Post reported that according to one official, Cassidy "apparently set his home on fire before going to the rail-yard facility and opening fire."
Deputy Russell Davis told reporters that a sheriff's office bomb squad remained at the VTA facility hours after the murders, explaining, "We received information that there are explosive devices that are located inside the building. We're trying to clear out every room, every crevice of that building."
"We're so sorry this event happened," VTA Board of Directors chairperson Glenn Hendricks said during a press conference. "We will do everything we can to help people get through this."
"It's just very difficult for everyone to be able to try to wrap their heads around and understand what has happened," he said, before praising VTA employees.
"These folks were heroes during COVID-19, the buses never stopped running, VTA didn't stop running," Hendricks added. "They just kept at work, and now we're really calling on them to be heroes a second time to survive such a terrible, terrible tragedy."
Karine Jean-Pierre, White House principal deputy press secretary, said during a briefing that the Biden administration "is monitoring the situation, and our hearts go out to the victims and their families."
"We still don't have all the details," Jean-Pierre said, "but what is clear, as the president has said, is that we are suffering from an epidemic of gun violence in this country, both in mass shootings and in the lives that are being taken in daily gun violence that doesn't make national headlines."