An Air France flight operating long-haul from Los Angeles (LAX) to Paris (CDG) has declared an emergency and is currently initiating a diversion to Reykjavík, Iceland.
Air France flight AF79, a Boeing 777-200ER operating a scheduled service from Los Angeles (LAX) to Paris Charles de Gaulle (CDG) declared a general emergency, squawking 7700 before initiating a diversion.

The aircraft in question is Air France Boeing 777-200ER, registered F-GSPF; a 24 year old airframe. Flight AF79 declared a general emergency in the cruise, before initiating the immediate diversion to nearby Keflavík International Airport (KEF).

The nature of the emergency is as yet unknown.

Updates for Air France AF79 Los Angeles – Paris
Flight AF79 declared a general emergency in the cruise, before initiating the immediate diversion to nearby Keflavík International Airport (KEF). The aircraft, a Boeing 777-200ER, is currently negotiating its approach to KEF, passing through 2,000 feet.

And the flight is now safely on the ground at KEF, after making a straight-in approach to RWY02. The aircraft is now safe on the ground, with the cause of the emergency unknown.

This is a developing story. Please check back for updates.
AviationSource will approach Air France for a comment on the cause of this transatlantic diversion into Keflavik, as the emergency was clearly serious enough for the diversion to occur and not continue onward to Paris from Los Angeles.
At the time of writing, they have not responded to our queries on this. But for now, more to follow in due course.

UPDATE @ 1739 UK time – Air France flight AF79, originally bound from Los Angeles to Paris, has departed from its diversion airport of Keflavik and is over the London Gatwick area.