Two workers at the Ralston Foods Inc. oat plant were shot and killed and another two were wounded Friday night. Police later arrested a plant employee at his home and charged him with murder.

Details of the shootings were not immediately available.

Gerald Rieflin, 35, surrendered to police after a twohour standoff at his Cedar Rapids home. He was charged with two counts of first-degree murder and two counts of attempted murder.

Officials did not release the identities of the victims. A plant employee, Donna Leach, said the two people who were killed had worked in the packaging department.