Both brothers finished the end of the swimming leg in the leading pack but Jonny was handed a penalty for mounting his bike too early after leaving Hyde Park's Serpentine lake.

CNN: Brownlee brothers take triathlon by storm

Gold in the men's open water 10-kilometer swimming marathon in the Serpentine, the lake in London's Hyde Park, went to Tunisian Oussama Mellouli.

CNN: August 10, 2012 -- Updated 2336 GMT (0736 HKT)