The reader was about to begin the Kedushah, when he was asked by Amnon to wait. The latter then recited the prayer known as  "Unetanneh Tokef," ("Let us tell how overwhelming [is the holiness of this day]") which is a description of the Day of Judgment.
The reader was about to start the Kedushah, when he was requested by Amnon to pause. The latter then recited the prayer known as  "Unetanneh Tokef," ("Let us recount how overwhelming [is the holiness of this day]") which is a description of the Day of Reckoning.