A recently laid-off tech employee Friday opened fire inside the Santa Clara office where he used to work, police said, killing three people, including the CEO and another top executive — and sparking a massive dragnet throughout the Bay Area.

Santa Clara police identified Jing Hua Wu, 47, of Mountain View as the man who shot to death two men and one woman with a handgun before driving off in a silver sport-utility vehicle, believed to be a rented Mercury Mariner.

Wu remained at large late Friday, and police warned he should be considered armed and “extremely dangerous.”

Friday’s violent scene erupted just before 4 p.m., when police say Wu arrived at SiPort, a small semiconductor company at 3255-7 Scott Blvd. and opened fire. Wu, an engineer, had apparently lost his job either Friday morning or Thursday, Santa Clara police Lt. Mike Sellers said.

When police arrived, the gunman already had escaped and was initially believed to be on his way to Mountain View, where police had staked out his home into the night. Other reports indicated he may have been headed to an airport.

Late Tuesday, police identified the two men killed as Sid Agrawal, the company’s chief executive, and Brian Pugh, vice president of operations for the company. The identity of the third victim had not been released as of early today.

SiPort is a relatively small company that specializes in developing digital radio semiconductors. It raised at least $20 million in venture capital last year.

Park Square, the complex that includes SiPort’s offices, was in lockdown immediately after the shooting as more than two dozen police officers blanketed the sprawling facility and cordoned off the buildings near Octavius Drive. Workers, meanwhile, huddled inside their offices as police with guns drawn cased the area.

Throughout the night, officers stopped and questioned employees in their vehicles as they left the complex.

And, hours later, employees in neighboring businesses were still shaken.

“I was on the computer and a co-worker was going home, and we heard this commotion,” said Linh Nguyen, a mechanical engineer who works next door at Excel Precision. “People were running inside our building, strangers, I didn’t know who they were. They were very upset, they looked disturbed and then we that three people had been shot.”

When Nguyen looked outside, he saw armed officers. So Nguyen and others locked their doors and waited.

“It’s very unreal to me,” said Nguyen, who added he didn’t know anyone who worked at SiPort. “With all these people being laid off, I mean, I know people are upset, but it’s hard to imagine that anyone would do this.”

Friday’s deaths were the third, fourth and fifth homicides this year in a city not accustomed to such spasms of violence.

“It’s certainly a tragedy any time someone feels like this is an action they have to take,” Santa Clara Police Chief Stephen Lodge said. “These are truly innocent people whose lives were taken. It’s just not right.”

In his SiPort biography, Agrawal is described as having more than 25 years of experience at both startups and established tech companies. He had held positions at Adobe Systems, Intel and Bell Labs, as well as at Alliance Semiconductor, Layer Five Networks and Synaptics.

Reached by a Mercury News reporter an hour after Friday’s shooting, his wife said she had not yet heard from her husband, and was worried that he hadn’t been picking up his cell phone. Agrawal’s family could not be reached later in the evening, after his identity was released.

Pugh also is listed on the SiPort biography as having 25 years of experience in semiconductor operations. He attended the University of California-Berkeley and Stanford University and had previously worked at Samsung and IBM.

According to a national study on workplace violence, such crimes account for 20 percent of all violent crime.

Although most workplace violence is not fatal, an average of 500 homicides occur in U.S. workplaces each year. Friday’s homicide by a worker who may have been upset about losing his job appears to be the first reported in the South Bay since the economy began to turn sour.

Wu, in some news reports, was said to have a wife and two children. He is described as 5-foot-11 and weighing 170 pounds, with black eyes and black hair. The Mercury Mariner he is believed to be driving has a license plate of 6CJU602.

People who encounter Wu are urged to keep their distance and call Santa Clara police immediately at (408) 615-4700. If Wu is in another city, witnesses should call 911 to reach that city’s police department.

Contact Sandra Gonzales at sgonzales@mercurynews.com or (408) 920-5778.