Exodus 19:16

19:16 On the third day in the morning there was thunder and lightning and a dense cloud on the mountain, and the sound of a very loud horn; all the people who were in the camp trembled.

Exodus 20:18

20:18 All the people were seeing the thundering and the lightning, and heard the sound of the horn, and saw the mountain smoking – and when the people saw it they trembled with fear and kept their distance.

Exodus 9:23-24

9:23 When Moses extended his staff toward the sky, the Lord sent thunder and hail, and fire fell to the earth; so the Lord caused hail to rain down on the land of Egypt. 9:24 Hail fell and fire mingled with the hail; the hail was so severe that there had not been any like it in all the land of Egypt since it had become a nation.