ASA 16A. Three umpires. Loser's bracket game, eight teams remaining on Saturday. I am U3.
1 out, R1 on 1B. A relatively routine grounder is hit to F6 and thrown to 2B to F4 for the force out. As F4 turns and begins to release the ball from her glove to throw to 1B, R1 slides into 2B, contacting F4's feet (still on the top of the base) with her feet, and knocking F4 to the ground hard.
EDIT for clarification: The BR is still two+ steps from 1B when this occurs.
What is your call?