Investigators continue to work at the scene near the heavy truck that ran into a crowd at high speed killing scores who were celebrating the Bastille Day July 14 national holiday on the Promenade des Anglais in Nice, France, July 15, 2016. REUTERS/Eric Gaillard

MOSCOW (Reuters) - Two U.S. citizens are among those killed in the truck attack in Nice, U.S. State Department spokesman John Kirby said in a statement on Friday.