(Updates number of dead, adds details on weapons)
By Emmett Berg
CUPERTINO, Calif Oct 5 (Reuters) - Three people were killed and seven were wounded when a disgruntled worker opened fire at a Northern California cement plant and then tried to steal a car, police said on Wednesday.
The gunman, identified as Shareef Allman, was also suspected of shooting a Hewlett Packard (HPQ.N) worker during an attempted carjacking a short time later in the HP parking lot, Santa Clara County Sheriff's spokesman Sgt. Jose Cardoza said.
Witnesses told detectives that a man matching Allman's description had run from the site of the second shooting, Cardoza said.
"We believe him to still be in the area. Several tactical teams are conducting yard-to-yard searches," Cardoza said.
Witnesses told police that Allman had arrived at a safety meeting at the Lehigh Southwest Cement Permanente Plant in Cupertino at about 4:30 a.m. armed with a handgun and rifle, and opened fire on roughly 15 of his co-workers, Cardoza said.
"He was unhappy and disgruntled, according to witnesses and victims," Cardoza said. "We don't know if it was work or family issues."
Witnesses and victims said Allman, in his 40s, later fled in a dark colored vehicle, Cardoza said.
"He should be considered armed and dangerous," Santa Clara County Sheriff Laurie Smith said at a press conference.
Police recovered four guns used in the attack, including a fully-loaded AK-47 or SKS assault rifle, roughly 150 yards from Allman's tan Mercury Cougar, a sheriff's deputy said.
The plant is part of Germany's HeidelbergCement AG (HEIG.DE), the world's No. 3 construction materials group.
"We are shocked and saddened by this morning's events," Dan Harrington, president and chief executive of Lehigh Hanson, said in a statement e-mailed to the media.
"Our thoughts and prayers are with the victims and their families. I have committed the company's resources to assist our affected employees during this difficult time."
Of the people shot at the plant, one was in critical condition after being shot in the face outside a meeting room, according to the deputy. Another was treated and released from a local hospital. The conditions of the other victims were not available.
"Today is a somber day. Our close-knit community was violently attacked, and we will continue to feel the shocks of this violence for some time." U.S. Representative Michael Honda said in a statement. His district includes Cupertino.
The deputy said that as Allman was trying to steal the car in HP's lot, another woman startled him as she left her car. He fired at her, then ran, the deputy said.
The driver who was shot was in fair condition at Santa Clara Valley Medical Center. She was not identified by police.
A spokesman for HP said that its campus had been closed because of the shooting, and that the company was working with local authorities. (Additional reporting by Mary Slosson, Dan Whitcomb and Ian Simpson; Editing by Jerry Norton and Cynthia Johnston)