CEDAR RAPIDS, Iowa (AP) _ A gunman opened fire at a Ralston Foods Inc. cereal plant, killing two workers and wounding two others, and a plant employee was arrested after a standoff at his home.

Assistant Police Chief Bruce Kern said investigators believed the gunman intended to shoot one of the workers, but that the others may have been ``at the wrong place at the wrong time.''

Police would not give details of the shootings and didn't know what set off the violence late Friday.

``Sometimes you never come up with definite motive,'' Kerns said.

After the shooting, police surrounded the home of Gerald Rieflin.

Family members and police negotiators persuaded Rieflin to give up after a two-hour standoff, Assistant Police Chief David Johnson said.

Police said they filed two charges of first-degree murder and two of attempted murder against Rieflin, 35. Kerns said Rieflin was talking to investigators today.

He said that after Rieflin surrendered, officers found a handgun inside the house and police believe it was the weapon used in the shootings.

Employee Donna Leach said the two who were killed work in the plant's packaging department and the wounded men work in the shipping department. The plant employes 200 people.

Rieflin, a long-time Ralston employee, was a stocker on the shipping dock working the night shift, Leach said.

The identities of the two dead workers were not released.

The two wounded workers were hospitalized in fair condition with leg wounds.