Elah was crowned to reign over Israel in the twenty-sixth year of Asa king of Judah and reigned for two years (vv. 6b, 8).
In the twenty-seventh year of Asa king of Judah, Zimri, the captain of half of Elah's chariots, conspired against Elah and struck him down. He then reigned in his place and destroyed all the house of Baasha (vv. 9-14).
Zimri was crowned in the twenty-seventh year of Asa king of Judah and reigned for just seven days (v. 15).
When the people heard that Zimri had struck down the king, they made Omri, the captain of the army, king over Israel that day in the camp (v. 16).
Omri with all the people of Israel besieged Tirzah. Zimri went up to the citadel of the king's house and burned the house over him with fire and committed suicide because he did evil in the sight of Jehovah and walked in the way of Jeroboam and in his sin by which he caused Israel to sin (vv. 17-20).