UPDATE: John Brownlee is fine. Both brothers collect their Olympic medals.
UPDATE: Race officials have announced that there will be a delay of 30 minutes because one of the runners is receiving medical attention. The competitor, reported to be John Brownlee, is "OK, just very fatigued".
UPDATE: According to reports from the finish line, John Brownlee has collapsed. His condition is unknown. The medal ceremony has been delayed. More to follow...
Alistair Brownlee, one half of Team GB's London Olympic triathlon brothers, managed to secure a gold medal in dramatic fashion after his closest rival - sibling Jonathan - was forced to take a 15-second penalty.
Draped in a Union flag, a shattered Brownlee slowed to a walk across the line before lying on his back and gasping for air.
As he finished in a time of 1.46.25 seconds, he appeared to be looking back for his brother - but he wasn't there.
Jonathan finally finished in bronze (time 1.46.56 seconds) after being given a frustrating standing penalty for getting on his bike too early in the transition from swimming to cycling.
The brothers, both dressed in black, hugged on the finishline as thousands of supporters cheered throughout Hyde Park.
The gold - remarkably Team GB's first ever medal in the event - means Britain has now equalled the first place haul of first places set in Beijing.
Earlier in the race, Jonathan was 4th after the swim, Alistair was 6th while fellow Briton Stuart Hayes was in ninth.
Moving in mirror image perfection for the transition from bike to running, the Brownlee brothers led the pack.
And it soon turned into a three-way race after the Brownlee brothers quickly broke away from the main pack with Spain’s Javier Gomez, who eventually finished in silver.
The brothers, watched by Lord Coe, had looked comfortable after the cycling leg, but tension rose after Brownlee’s penalty was announced over the PA.
He had to complete the 15-second punishment shortly before going into the final lap of the 10km run.
here were jubilant scenes in the Brownlee brothers' home city of Leeds as hundreds watched them win gold and bronze Olympic medals.
Crowds in Millennium Square cheered and stamped their feet as the brothers finished in first and third places.
Chants of "Brownlee, Brownlee" rang out around the square as around 500 people watched the triathlon on a big screen.