Amon's officials conspired against him and assassinated1 the king in his palace.
References for 2 Kings 21:23
Then the people of the land killed2 all who had plotted against King Amon, and they made Josiah3 his son king in his place.
References for 2 Kings 21:24
As for the other events of Amon's reign, and what he did, are they not written in the book of the annals of the kings of Judah?
He was buried in his grave in the garden4 of Uzza. And Josiah his son succeeded him as king.
References for 2 Kings 21:26