When Zimri saw that the city was captured, he entered the citadel of the royal palace and burned it down upon himself. So he died
KJV
And it came to pass, when Zimri saw that the city was taken, that he went into the palace of the king’s house, and burnt the king’s house over him with fire, and died,
ASV
And it came to pass, when Zimri saw that the city was taken, that he went into the castle of the king’s house, and burnt the king’s house over him with fire, and died,