What does 2 Kings 1:12 mean?

Elijah answered the captain, 'If I'm really a man of God, let fire come down from the sky and burn up you and your fifty men.' And fire came down from the sky and burned them up. 2 Kings 1:12 - Modern Text Bible

(Elijah calls down fire as a sign of God's power and judgment, showing that God's authority is greater than the king's.)