An employee opened fire Wednesday at a California rail yard, killing eight people before taking his own life as law enforcement rushed in, authorities said, marking the latest attack in a year that has seen a sharp increase in mass killings as the nation emerges from coronavirus restrictions.

The shooting took place around 6:30 a.m. in two buildings that are part of a light rail facility for the Valley Transportation Authority, which provides bus, light rail and other transit services throughout Santa Clara County, the most populated county in the San Francisco Bay Area. The facility in San Jose includes a transit-control center, parking for trains and a maintenance yard.

“When our deputies went through the door, initially he was still firing rounds. When our deputy saw him, he took his life,” Santa Clara County Sheriff Laurie Smith told reporters. Deputies “were going through hallways saying, ‘Sheriff’s office!’ He knew at that time that his time for firing shots was over.”

A man who was wounded was in critical condition at Santa Clara Valley Medical Center, spokesperson Joy Alexiou said.

The attacker was identified as 57-year-old Sam Cassidy, according to two law enforcement officials. Investigators offered no immediate word on a possible motive.

His ex-wife, Cecilia Nelms, told The Associated Press that Cassidy had a bad temper and would tell her that he wanted to kill people at work, “but I never believed him, and it never happened. Until now.”

Nelms said they were married for 10 years - Cassidy filed for divorce in 2005 - and had not been in contact for 13 years. She said he had been treated for depression.

Sheriff's spokesman Deputy Russell Davis said he did not know the type of weapon used in the attack. Bomb squads were searching the rail complex after receiving information about possible explosive devices, he said.

Members of a union representing Valley Transportation Authority workers were meeting when the shooting began, San Jose Mayor Sam Liccardo said, but it’s not clear it was related to the attack.

When she heard shots, transit authority mechanic Rochelle Hawkins said she dropped her phone.

“I was running so fast, I just ran for my life,” she said. “I would hope everyone would just pray for the VTA family. Just pray for us.”

Authorities did not identify the victims, who included transit employees. Grief-stricken families sat huddled together after learning they had lost a loved one, District Attorney Jeff Rosen told reporters.

“They’re just sitting and holding hands and crying,” Rosen said. “It’s terrible. It’s awful. It’s raw. People are learning they lost their husband, their son, their brother.”

Officials also were investigating a house fire that broke out shortly before the shooting, Davis said. Public records show Cassidy owned a two-story home where firefighters responded. Fire crews found a fast-moving blaze after being notified by a passer-by. A neighboring house also caught fire, authorities said.

Doug Suh, who lives across the street from Cassidy, told The Mercury News in San Jose that Cassidy was “lonely” and “strange” and that he never saw anyone visit.

“I’d say hello, and he’d just look at me without saying anything,” Suh said. Once, Cassidy yelled at him to stay away as he was backing up his car. “After that, I never talked to him again.”

Cassidy had worked for Valley Transportation Authority since at least 2012, according to the public payroll and pension database known as Transparent California. His position from 2012 to 2014 was listed as a mechanic. After that, he maintained substations, the records said.

Trains were already out on morning runs when the shooting occurred. Light rail service was suspended and replaced with bus bridges, agency Chairman Glenn Hendricks told reporters.

Gov. Gavin Newsom, speaking emotionally in front of a county office where flags flew at half-staff, said victims' relatives were "waiting to hear from the coroner, waiting to hear from any of us, just desperate to find out if their brother, their son, their dad, their mom is still alive.”

The bloodshed comes amid a rise in mass killings after the pandemic had closed many public places and kept people confined to their homes last year.

A database compiled by The Associated Press, USA Today and Northeastern University that tracks every mass killing over the last 15 years shows that the San Jose attack is the 15th mass killing so far in 2021, all of them shootings.

Eighty-six people have died in the shootings, compared with 106 for all of 2020. It is the sixth mass killing in a public place in 2021. The database defines mass killings as four people dead, not including the shooter, meaning the overall toll of gun violence is much higher when adding in smaller incidents.

At the White House, President Joe Biden ordered flags to be flown at half-staff and urged Congress to act on legislation to curb gun violence.

“Every life that is taken by a bullet pierces the soul of our nation. We can, and we must, do more,” Biden said in a statement.

San Jose, the 10th-largest city in the U.S. with more than a million people, is about 50 miles (80 kilometers) south of San Francisco in the heart of Silicon Valley.

Wednesday's attack was Santa Clara County's second shooting in less than two years. A gunman killed three people before killing himself at a popular garlic festival in Gilroy in July 2019.

Two of the victims in the Gilroy shooting - a 6-year-old boy and a 13-year-old girl - had lived in San Jose. Their deaths were on Mayor Liccardo's mind Wednesday as text messages flooded in, reporting the active shooter and fire.

“Not again," he thought as he jumped in his car and raced to City Hall. Transit authority workers told him they knew Cassidy.

“You try to understand what would possess someone to do that much harm," Liccardo said by phone. "It’s unfathomable.”