1 Kings 16:15-17

15In the twenty-seventh year of Judah’s King Asa, Zimri became king for seven days in Tirzah. Now the troops were encamped against Gibbethon of the Philistines.

16When these troops heard that Zimri had not only conspired but had also struck down the king, then all Israel made Omri, the army commander, king over Israel that very day in the camp.

17Omri along with all Israel marched up from Gibbethon and besieged Tirzah.