NEW : Shooting in Federal Way , Washington , began with domestic dispute , police say . NEW : Police are investigating a shooting at the home of an FBI agent who was shot and killed by his wife while they were arguing over custody of their children. The gunman then returned to his apartment and retrieved a shotgun , he said . NEW : Ties between gunman , three of the victims are unclear , police chief says . Shots were still being fired when officers arrived , police spokeswoman says .
NEW : Shooting in Federal Way , Washington , began with domestic dispute , police say . NEW : Police are investigating a shooting at the home of an FBI agent who was shot and killed by his wife while they were arguing over custody of their children. NEW : Ties between gunman , three of the victims are unclear , police chief says . Shots were still being fired when officers arrived , police spokeswoman says .