All the people witnessed the thunder and lightning, the sound of the trumpet, and the mountain [surrounded by] smoke. When the people saw [it] they trembled and stood at a distance.
References for Exodus 20:18
"You speak to us, and we will listen," they said to Moses, "but don't let God speak to us, or we will die."
Moses responded to the people, "Don't be afraid, for God has come to test you, so that you will fear Him and will not sin."
References for Exodus 20:20
And the people remained standing at a distance as Moses approached the thick darkness where God was.