Albert Barnes Commentary John 12:29

"The multitude therefore, that stood by, and heard it, said that it had thundered: others said, An angel hath spoken to him." — John 12:29 (ASV)

The people. A part of the people.

It thundered. The unexpected sound of the voice would confound and amaze them; and though there is no reason to doubt that the words were spoken distinctly (Matthew 3:17), yet some of the people, either from amazement or envy, would suppose that this was a mere natural phenomenon.

An angel spake. It was the opinion of many of the Jews that God did not speak to men except by the ministry of angels, Hebrews 2:2: The word spoken by angels; Galatians 3:19: It was ordained by angels in the hand of a mediator.