An American was killed and five were injured in a deadly train derailment in northwest Spain, the State Department said Thursday.
They were among at least 80 fatalities and scores of injuries in one of the worst railway disasters in Spain's history.
A State Department spokesman did not provide details of the American casualties.
President Obama offered "heartfelt gratitude to the government of Spain and to the rescue personnel who are working to locate the missing and treat the injured – including at least six Americans."
"Today the American people grieve with our Spanish friends, who are in our thoughts and prayers," Obama said in a statement. "We stand ready to provide any assistance we can in the difficult days ahead."
Spanish Prime Minister Mariano Rajoy has promised two investigations into the tragedy, which took place Wednesday evening near the Christian pilgrimage town of Santiago de Compostela in the Galicia region.
Suspicion focused Thursday on excessive speed as a possible cause. Security camera footage showed the train traveling at what appeared to be a high rate of speed as it rounded a bend. Carriages jumped off the tracks and slammed into a security wall.
The train was en route from Madrid to the port town of Ferrol when it derailed with 218 passengers on board. After the disaster, Santiago de Compostela canceled a major religious festival that attracts thousands of pilgrims from all over the world.