FRESNO, Calif. (AP) — That Lawrence Jones targeted a handful of his co-workers at a chicken-processing plant, killing two of them execution-style, was evident, authorities said. But why he did it remained unclear.

"He had opportunity to shoot other co-workers that were in the business at this time, but he chose not to," Fresno Police Chief Jerry Dyer said. "He walked around them in order to get very close to the intended targets, place the gun very close and fire a round."

Clattering machinery at the plant provided all the cover he needed for the shooting Tuesday, leaving two dead and wounding two others, authorities said. Jones opened fire at a fifth person but ran out of bullets, police said, although he later reloaded and shot himself in the head.

Armed with a handgun, the 42-year-old ex-convict moved methodically from victim to victim, placing his handgun against their head or neck and then pulling the trigger, authorities said.

The unsuspecting victims had on ear protectors as they worked just feet apart in the deboning room and the grinding room at Valley Protein. The gunshots were drowned out by the machinery.

By then, his gun was out of ammunition. Jones walked out of the building, reloaded, placed the gun against his head and fired. He was pronounced dead at a hospital a few hours later.

Jones' motive was unknown, but it was clear he had targeted his victims, Dyer said. About 30 employees were working at the plant during the shooting.

Some workers told police Jones did not appear to be himself when he arrived for his shift.

"We are still trying to follow up on some rumors regarding a dispute between Jones and one of the other co-workers, but we have not been able to verify it at this point," Dyer said.

Jones, who had worked at the plant for 14 months, had an extensive criminal history, authorities said. In 1994, he was sentenced to 13 years in prison for robbery, then released on parole in 2001, according to the state Department of Corrections and Rehabilitation.

Jones also served time for robbery and later for vehicle theft and other convictions, and was paroled on June 1, 2011, department spokesman Luis Patino said. He was discharged from parole on May 1, 2012, Patino said.

"He was reviewed and he had not had any violations and so he was discharged from parole," Patino said.

Dyer said Jones arrived at work on a bike just before 5 a.m. About three-and-a-half hours into his shift, he pulled out the handgun.

First, Jones silently walked up to 32-year-old Salvador Diaz in the grinding room, put the handgun to the side of his head and pulled the trigger, police said. Diaz was pronounced dead at the scene.

Jones then went next door to the deboning room, put the gun up against the head of the second victim, 34-year-old Manuel Verdin, and pulled the trigger. Verdin was pronounced dead at a hospital.

Jones shot the third victim, Arnulfo Conrriguez, 28, in the neck at close range, police said. Conrriguez was in serious condition at Fresno's Community Regional Medical Center, hospital spokeswoman Mary Lisa Russell said.

A fourth victim, 32-year-old Fatima Lopez, witnessed the slayings and started to run. Jones shot at her, striking her in the buttocks. Lopez was treated at Community Regional Medical Center and released, Russell said.

Attempts by The Associated Press to reach Lopez for comment were not immediately successful. Continued...