A central Iowa policeman shot and killed a man last night.Marshalltown police responded to a 9-1-1 call about 5 P.M. about a man with a gun in the yard of a home. Police chief Lon Walker says an officer arrived and found the man, who refused to drop his weapon. Police say the man fired one shot at the officer who returned fire and killed him. The dead man’s name hasn’t been released. The officer has been placed on administrative leave, but Chief Walker says that’s standard. Walker says the preliminary findings are that the officer was “100-percent justified” in shooting the man. An autopsy is planned today.