Compare:
And now the astonishment of Alma was so great that he became dumb, that he could not open his mouth; yea, and he became weak, even that he could not move his hands; therefore he was taken by those that were with him, and carried helpless, even until he was laid before his father.
Mosiah 27:19
And he began to cry unto the Lord, saying: O Lord, have mercy; according to thy abundant mercy which thou hast had upon the people of Nephi, have upon me, and my people.
And now, when he had said this, he fell unto the earth, as if he were dead.Alma 18:41-42
And it came to pass that when Aaron had said these words, the king did bow down before the Lord, upon his knees; yea, even he did prostrate himself upon the earth, and cried mightily, saying:
O God, Aaron hath told me that there is a God; and if there is a God, and if thou art God, wilt thou make thyself known unto me, and I will give away all my sins to know thee, and that I may be raised from the dead, and be saved at the last day. And now when the king had said these words, he was struck as if he were dead.Alma 22:17-18
Why was it that whenever someone was converted, he “was struck as if he was dead”? Well, what did they say after they woke up again?
I have repented of my sins, and have been redeemed of the Lord; behold I am born of the Spirit.
And the Lord said unto me: Marvel not that all mankind, yea, men and women, all nations, kindreds, tongues and people, must be born again; yea, born of God, changed from their carnal and fallen state, to a state of righteousness, being redeemed of God, becoming his sons and daughters;
And thus they become new creatures; and unless they do this, they can in nowise inherit the kingdom of God.
I say unto you, unless this be the case, they must be cast off; and this I know, because I was like to be cast off.
Nevertheless, after wading through much tribulation, repenting nigh unto death, the Lord in mercy hath seen fit to snatch me out of an everlasting burning, and I am born of God.
My soul hath been redeemed from the gall of bitterness and bonds of iniquity. I was in the darkest abyss; but now I behold the marvelous light of God. My soul was racked with eternal torment; but I am snatched, and my soul is pained no more.
I rejected my Redeemer, and denied that which had been spoken of by our fathers; but now that they may foresee that he will come, and that he remembereth every creature of his creating, he will make himself manifest unto all.
Yea, every knee shall bow, and every tongue confess before him. Yea, even at the last day, when all men shall stand to be judged of him, then shall they confess that he is God; then shall they confess, who live without God in the world, that the judgment of an everlasting punishment is just upon them; and they shall quake, and tremble, and shrink beneath the glance of his all-searching eye.Mosiah 27:24-31
Blessed be the name of God, and blessed art thou.
For as sure as thou livest, behold, I have seen my Redeemer; and he shall come forth, and be born of a woman, and he shall redeem all mankind who believe on his name.Alma 19:12-13
O blessed Jesus, who has saved me from an awful hell! O blessed God, have mercy on this people!
Alma 19:29
Alma was tormented, then repented and spoke to God. Lamoni repented and then saw Jesus. The queen said Jesus saved her, but he can only save the righteous, so she must have also repented. I assume she also talked to God and/or Jesus because how else would she learn about him?
They fell because that must be how God showed himself to them.