Question

What are thunderclap these words were to me why does the writer say so?

Answer 1

As Franz entered his class and sat at his seat, he found the class already packed to capacity. He found M. Hamel pacing up and down in the class; he was in his best clothes. After everyone settled he said, "My children, this is the last lesson I shall give you. The order has come from Berlin to teach only German in the schools of Alsace and Lorraine. The new master comes to-morrow. This is your last French lesson. I want you to be very attentive.”

These quoted words of M. Hamel were a thunder clap, which shocked Franz (the narrator