The Napa Police Department announced Friday on its Web site that it is investigating the incident that occurred at Raiders training-camp headquarters on Aug. 5, when assistant coach Randy Hanson told police he suffered injuries that resulted in him being treated at an emergency room.

Raiders defensive assistant Randy Hanson, who told police he was injured after being struck by another member of the team’s coaching staff Aug. 5, has retained an attorney to represent him, according to a source with knowledge of the situation.