2 Chronicles 22:10

So when Athaliah, the mother of Ahaziah, saw that her son was dead, she arose and destroyed all the royal seed of the house of Judah.

2 Kings 11:1-3

And Athaliah, the mother of Ahaziah, seeing that her son was dead, arose and destroyed all the royal seed.

2 Chronicles 22:2-4

Ahaziah was forty-two years old when he began to reign, and he reigned one year in Jerusalem. His mother's name was Athaliah, the daughter of Omri.

Treasury of Scripture Knowledge

Summary

But when Athaliah the mother of Ahaziah saw that her son was dead, she arose and destroyed all the seed royal of the house of Judah.

Bible References

Athaliah

2 Chronicles 22:2
Ahaziah was forty-two years old when he began to reign, and he reigned one year in Jerusalem. His mother's name was Athaliah, the daughter of Omri.
2 Kings 11:1
And Athaliah, the mother of Ahaziah, seeing that her son was dead, arose and destroyed all the royal seed.