Obstruction

[finfan]

IHSA Fastpitch (NFHS) Runner on third base, the ball is hit to the second baseman. The second baseman fields the ball and throws to the first baseman. The Batter/runner is running toward first base down the middle of the first base line,(one foot in fair territory and one foot in foul territory), the first baseman throws the ball in attempt to throw the runner out who is attempting to score at home plate but the throw hits the batter/runner in the left arm/side. What is the appropriate call? Is this in fact interferrence, and is the runner attempting to score also out?