Authorities went door to door with guns drawn Wednesday in search of a disgruntled employee they say opened fire at a Northern California limestone quarry, killing three and injuring six before wounding another woman in an attempted carjacking.

Schools were on lockdown in the Silicon Valley city of Cupertino and nearby Los Gatos as SWAT teams sought Shareef Allman, 47, of San Jose.

Allman was at a routine safety meeting at the quarry at about 4:30 a.m. when he became disgruntled and left, authorities said. He then returned with a handgun and rifle and started shooting people, Santa Clara County Sheriff's Lt. Rick Sung said. About 15 workers were at the meeting.

Sheriff Laurie Smith said two people were pronounced dead at Permanente Quarry in Cupertino, and a third person died later at the hospital.

Six others at the quarry were wounded and taken to area hospitals, Smith said. Some of them remained in critical condition, she said.

Authorities located Allman's vehicle and have seized a shotgun, a handgun and two rifles believed to belong to the suspect, Smith said.

"The challenges are the big geographical area," she said. "The challenges are that he's armed."

Around 7 a.m., authorities received a 911 call that a woman was shot in an attempted carjacking near Hewlett-Packard Co.'s Cupertino campus by a man matching Allman's description. The shooter then fled on foot.

He used a weapon similar to a gun used in the quarry shooting, authorities said.

The carjacking victim, a Hewlett-Packard contract employee, was listed in fair condition at Santa Clara Valley Medical Center, according to hospital spokeswoman Joy Alexiou. Another victim was treated and released from the hospital, while a third remained in fair condition, she said.

Allman was last seen in surveillance footage from a nearby gas station shortly after the shooting outside Hewlett-Packard, Smith said. In the video, he appeared to be armed, she said.

In addition to working at the quarry, Allman has run a nonprofit group for youths and produced and hosted a public access television show for CreaTV in San Jose.

Suzanne St. John-Crane, executive director of CreaTV, said she had spoken with him numerous times but did not know him well.

"Based on what we know now, we're shocked and devastated and feel for the families of the victims," St. John-Crane told The Associated Press. "But he didn't work here. I want to make that clear. We're very frightened."

A video posted on YouTube shows Allman interviewing the Rev. Jesse Jackson outside a memorial for the late musician Walter Hawkins for a piece for CreaTV. In the video, Allman talks with Jackson about the positive and transformative messages of gospel music

"I hope what he gave all of us we take out to our community and use it to better ourselves and our community," Allman said about Hawkins during the interview.

Business records show that in 2004, Allman started a youth development organization called Helping Hands Changing Hearts, which listed its location as Allman's home address. However, the IRS automatically revoked the organization's exempt status as a nonprofit for failure to file proper tax forms for three consecutive years, records showed.

The shootings rattled those who know Allman, said Paulette Conner, a neighbor in his San Jose apartment complex. Police were still talking to Allman's teenage daughter inside their apartment late Wednesday morning, she said.

"He's always had a smile on his face," said Conner, 57, who has known Allman for five years. "I've never known him to have any violent tendencies. Never. Ever."

Conner said Allman occasionally griped to her and others over the years about his job, including his various shift changes and some co-workers, but she never imagined that he could do something violent. She said Allman is a local fixture who has been heavily involved in San Jose's black community.

"He is very kind, sociable person and a really good father," Conner said. "I've never known him to be a mean person."

The Permanente Quarry is a limestone and aggregate mining operation and cement plant owned by Lehigh Southwest Cement.

"Our thoughts and prayers are with the victims and their families," Dan Harrington, president and chief executive of parent company Lehigh Hanson Inc., said in a statement. "I have committed the company's resources to assist our affected employees during this difficult time."

The quarry was issued its first permit in May 1939, according to Santa Clara County documents.

The site has been subject to a number of environmental violations over the years, and has been subject to noise and other complaints from residents who live nearby.

Lehigh makes about 1.2 million tons of cement per year, and its products are involved in a number of major construction projects including the seismic upgrades to the Golden Gate Bridge.

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Associated Press writers Jason Dearen, Terry Collins, Sudhin Thanawala and Beth Duff-Brown and photographer Paul Sakuma contributed to this report.