What would you do?

[CVO2]

Runners on 1st and 3rd no out.
F1(rightie) has a very quick step off and throw pick move. I'm in B

F1 begins the pick move, my head goes to first, no ball, i look back and catch very end of play at 3rd.
He had a great fake to first (fooled me) and very quick turn and throw to third.
Like I said when I turn and focus all I see is runner in prone position on the bag and F5 with glove on arm.
I have no idea if it was safe or out.
What would you do?