Exodus 19:16
And it came to pass on the third day in the morning, that there were thunders and lightning, and a thick cloud on the mount, and the voice of the trumpet exceeding loud; so that all the people that was in the camp trembled.
Torrey's Topical Textbook—AKJV

Exodus 20:18
And all the people saw the thunder, and the lightning, and the noise of the trumpet, and the mountain smoking: and when the people saw it, they removed, and stood afar off.
Torrey's Topical Textbook—AKJV