The shooting happened about five miles from the quarry. Mike Astor, who manages a gas station near the scene, told The Associated Press that he heard gunshots around 7:30 a.m.
According to authorities, Allman became upset Wednesday during a safety meeting at Permanente Quarry. Allman left the meeting and returned with a handgun and rifle and started shooting people, Santa Clara County sheriff's Lt. Rick Sung. About 15 workers were at the meeting.
Santa Clara County Sheriff Laurie Smith released the names of the dead Wednesday evening as Manuel Pinon, 48, of Newman, Calif., and John Vallejos, 51 and Mark Munoz, 59, both of San Jose.
Six others at the quarry were wounded and taken to hospitals, where some remained in critical condition, Smith said.
Later Wednesday morning, authorities received a 911 call reporting 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 fled on foot after using a weapon similar to a gun used in the quarry shooting, authorities said.
The carjacking victim, a Hewlett-Packard contract employee, was 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.
Schools were locked down in Cupertino, home of Apple Inc., and in nearby communities as authorities went door to door with guns drawn and residents were warned to stay indoors.
Authorities found Allman's car, and collected a shotgun, a handgun and two rifles believed to belong to the suspect, Smith said, adding that some of the weapons were found in the car.
The shootings rattled those close to Allman.
To his friends, Allman was the big man with a big smile, a devoted single father of two who once worked tirelessly to raise money for Hurricane Katrina victims, and who penned a novel about the evils of domestic violence.