Interference, Obstruction, or Incidental Contact?

[Gre144]

BR hits a grounder to F6 who throws the ball to F3. The throw forces F3 to step with part of his left foot and his body into the running lane. However, he legally has his right foot on the bag and in fair territory when a collision occurs between him and BR. (BR is running properly in the the running lane). BR is hurt from the collision and the ball rolls towards the fence.

What call would you make?

Also, would you call time immediately because of the injury or wait until all playing action has ended? In this game, the ball was at the dugout fence at the time of the collision. The runner, on second, decided not to advance because he was so focused on the collision. Also, not one fielder attempted to pick up the ball.(Fed Rules please)

Thanks,

Greg