LINCOLN -- Lincoln Police are working on four armed robberies that happened over a course of six hours Tuesday evening. Sgt. Tarrence Vernon tells KFOR NEWS a man was robbed by an armed man in the 46th and Randolph neighborhood around 5:30pm. The victim is okay. Then around 8:30pm, four men robbed a man on A Street between 19th and 20th. One man had a gun. A short time later, four men then tried to rob a man walking home from a grocery store near 21st and "A", but came away with nothing. Then in the 1600 block of D Street, a pizza delivery driver is robbed by an armed man.