In the twenty-sixth year of Judah's King Asa, Elah, Baasha's son, became king over Israel. He ruled in Tirzah for two years.
References for 1 Kings 16:8
Zimri, his officer who led half the chariots, plotted against him. Elah was at Tirzah, getting drunk at the house of Arza, who had charge over the palace at Tirzah.
Zimri came, attacked, and killed Elah in the twenty-seventh year of Judah's King Asa. Zimri succeeded him as king.
Once Zimri became king and sat on the throne, he attacked all of Baasha's house. He didn't spare anyone who urinates on a wall, whether relative or friend.
Zimri destroyed the entire house of Baasha in agreement with the LORD's word that had been spoken by the prophet Jehu to Baasha.
This happened because of all Baasha's sins, as well as the sins of his son Elah and because they caused Israel to sin. They angered Israel's God, the LORD, with their insignificant idols.
The rest of Elah's deeds and all that he did, aren't they written in the official records of Israel's kings?