**Atalyah** daughter of Achav, wife of Yehoram son of Yehoshafat, reigned for 6 interrupted years [(see Chiddushei HaRama"h section 7)] from year 3056 until 3060, and she was killed after the death of her son King Achazyahu. She killed all the seed of the house of David except Yoash son of Achazyahu who was one year old, whom Yehosheva [(in Tzeda there's a typographical error)] daughter of King Yehoram, wife of Yehoyada, rescued and hid for 6 years [(Melachim II 11)] [(Tzeda)].
In the hot season he was in the upper chamber of the Temple, and in the rainy season in the chambers [(Yalkut there 12:309)]. Yehoyada her husband was the High Priest and Elisha the prophet. [Sha'ar HaDorot 18:2 writes: I saw in the book of Philo the Jew that King David commanded that the youngest of his sons would reign, which is Shlomo, and if he or his seed would die without surviving offspring, then offspring greater than him would reign in his place, who is Natan, and these are called "brothers of the prince" as appears (Melachim II 5).
And according to this opinion, until Yehoshafat and Achazyahu the seed of Natan was called "brothers of the princes," and thus the men that Yehoram killed (see year 50) were the seed of Natan as appears (Divrei HaYamim II chapter 21), and Yehoram alone remained from the seed of Shlomo. When he was killed, Atalyah strove to kill all the royal seed from the "brothers of the princes," and Yoash remained who is also called first and foremost, and he was the first of the seed of David and the remnant of the seed of Natan was his son, thus far.]