June 25 (Bloomberg) -- A 25-year-old man armed with a handgun shot six co-workers at a western Kentucky plastics plant, killing five, before taking his own life.

Wesley Neal Higdon opened fire early today following an argument with a supervisor at the Atlantis Plastics Inc. factory in Henderson, the Ohio River town's police force said in a statement.

``The cause behind this incident is unknown; however, the suspect is known to have gotten into an argument with a supervisor earlier in the evening,'' according to the police force's statement.

``After this argument, the suspect left the building for his regular break,'' said the statement. ``When he returned, he had the handgun with him.''

Police said Trisha Mirelez, 25, and the gunman were pronounced dead at the scene. Kevin G. Taylor, 30, and Rachael Vasquez, 26, died at Methodist Hospital in Henderson. Joshua Hinojosa, 28, and Israel Monroy, 29, died at hospitals in Evansville, Indiana.

Noelia Monroy, 22, suffered multiple gunshot wounds and is in stable condition at St. Mary's Hospital in Evansville, the statement said.

Atlantis Plastics Chief Executive Officer Bud Philbrook told the Associated Press the killings were a ``total shock.''

The plant produces injection-molded products, according to the Atlanta-based company's Web site. Henderson is 232 miles (373 kilometers) west of Louisville.

To contact the reporter on this story: Robin Stringer in New York at rstringer@bloomberg.net.

Last Updated: June 25, 2008 16:46 EDT