2 Chronicles 22:7-11

Now the destruction of Ahaziah was from God, in that he went to Joram. For when he arrived, he went out with Jehoram against Jehu the son of Nimshi, whom the Lord had anointed to eliminate the house of Ahab. Jehu Murders Princes of Judah

And it came about, when Jehu was executing judgment on the house of Ahab, that he found the princes of Judah and the sons of Ahaziah’s brothers attending to Ahaziah, and killed them.

He also searched for Ahaziah, and they caught him while he was hiding in Samaria; they brought him to Jehu, put him to death, and buried him. For they said, “He is the son of Jehoshaphat, who sought the Lord with all his heart.” So there was no one of the house of Ahaziah to retain the power of the kingdom.

Now when Athaliah the mother of Ahaziah saw that her son was dead, she rose and eliminated all the royal children of the house of Judah.

But Jehoshabeath the king’s daughter took Joash the son of Ahaziah, and stole him from among the king’s sons who were being put to death, and placed him and his nurse in the bedroom. So Jehoshabeath, the daughter of King Jehoram, the wife of Jehoiada the priest (for she was the sister of Ahaziah), hid him from Athaliah so that she would not put him to death.