Could you please help me correct/improve the sentences

Man on phone: I'm going to throw him off the building.

Christian: Please don't.

Man on phone: Too late.

(1) Christian looks up at the building and just then a man is being thrown through a window and dropping to the ground.

(2) Just then a window is heard breaking and Christian looks up at the building to see a man dropping to the ground.

(3) Christian looks up at the building to see a man being thrown through a window and dropping to the ground.

Could you please help me correct/improve the three sentences for me so they are good?

Which one of the sentences is the better one do you think? If none of them, how would you write it instead?

Thank you in advance.