(Reuters) — A poultry processing plant employee opened fire on his co-workers on Tuesday in Fresno, Calif., killing a man and injuring three people before critically wounding himself, police said.

The gunman, identified as Lawrence Jones, 42, opened fire at the facility and killed a 32-year-old man, Police Chief Jerry Dyer told reporters.

Mr. Jones, who has a criminal history and was found by officers on the sidewalk near the plant with a self-inflicted gunshot wound to the head, and the four people he shot were all employees of the business, Chief Dyer said.

A 34-year-old worker at the plant was shot in the head and a 28-year-old male employee was hit in the neck, Chief Dyer said. Both men were hospitalized in critical condition, police said.

A 32-year-old woman was shot in the lower back but is in good condition, police said. She was found outside the plant, but investigators believe she was shot inside the facility.

About 30 workers inside the plant are believed to have witnessed the shooting, and roughly another 30 were there but did not see what happened, Chief Dyer said.

Chief Dyer initially said the plant is called Apple Valley Farms, but city of Fresno spokesman Michael Lukens later said the business recently changed its name to Valley Protein. The facility processes poultry, he said.

The plant where the shooting occurred is a windowless, rectangular warehouse set back from the street and near an antique store and a railroad track, in a mixed commercial and industrial area.

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After the shooting, employees' relatives gathered anxiously outside, hoping to be reunited with loved ones.

Fresno, a city with a population of about 500,000, is located 160 miles southeast of San Francisco and is surrounded by farmland in the San Joaquin Valley.

"This was a senseless, violent act that affects our entire community," Mayor Ashley Swearengin said in a statement.

"Anytime you have an incident where you have multiple people that are shot, people that are deceased and it includes workplace violence like this ... it is a tragedy," Chief Dyer said. He said police hope to determine a motive for the shooting.

Joe Martinez, 45, was sitting at the drive-through window at a McDonald's across the street from the shooting, and said he witnessed the end of it.

"All I heard was boom and I immediately looked over and see three people, and then one drops to the ground," Mr. Martinez said.

The person who fell was the gunman, Mr. Martinez said, and that it looked like the shooter was chased out of the plant.

Mr. Jones reported for work before dawn and his co-workers noticed that he "did not appear to be himself," Chief Dyer said. Mr. Jones was at the meat processing plant for more than three hours before opening fire with a handgun, Chief Dyer said.

"It's difficult to say if there was a specific target that Jones was looking for," he said.

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Police have not released the names of the four employees they say were shot by Mr. Jones. A representative for Valley Protein could not be reached for comment.

Mr. Jones has worked at the plant for the past 14 months and has a criminal history dating to the 1990s, Chief Dyer said.

Officers have gone to Mr. Jones' home in Fresno and they are seeking to determine if he might have attacked anyone else before going to work, Chief Dyer said.

He is hospitalized in critical condition, police said.