The attackers of Samuel the Lamanite were the Nephites at Zarahemla who rejected his preaching from the city wall, where he testified that Christ would come and called the people to repent. Those who did not believe were angry with him and cast stones and shot arrows at him as he stood on the wall, but they could not hit him because the Spirit of the Lord was with him (Helaman 16:2).
When they saw they could not hit him, they cried to their captains to seize and bind Samuel, saying he had a devil and that it was the devil’s power in him that kept their stones and arrows from striking him (Helaman 16:6).