Knocking Ecthelion's sword out of his hands, Gothmog prepared to strike at him but, as he raised his axe, Ecthelion ran forward at the Balrog lord, ramming his pointed helmet into the beast's chest and forcing both of them into the Fountain of the King. The waters quenched the flames of Gothmog that kept him alive and drowned Ecthelion, ending the Battle of Gondolin.
The Silmarillion by J.R.R. Tolkien