So far 73 bodies have been recovered from the scene in Spain's Galicia region, while four people died in hospital, a spokeswoman for Galicia supreme court said Thursday, according to the BBC.
More than 160 people were injured, at least 30 of them seriously. Emergency services personnel continued to search for people still trapped in the wreckage throughout the night.
"The scene is shocking, it's Dante-esque," Alberto Nunez Feijoo, the head of the Galicia region, said in a radio interview late Wednesday, according to the Guardian.
Spain's prime minister, Mariano Rajoy, who was born in Santiago, visited the scene of the accident on Thursday.
"In the face of a tragedy such as just happened in Santiago de Compostela on the eve of its big day, I can only express my deepest sympathy as a Spaniard and a Galician," said Rajoy in a statement.
"For someone from Santiago, like myself, believe me, this is the saddest Day of Saint James of my life," he added.
The train was carrying 218 passengers in addition to crew members when it derailed en route from Madrid to El Ferrol on the Galician coast, Spain's state-owned Renfe train company said, reported The Wall Street Journal.
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"A lot of people were squashed on the bottom. We tried to squeeze out of the bottom of the wagons to get out, and we realized the train was burning," passenger Ricardo Montesco told Cadena Ser radio station, according to the Guardian. "I was in the second wagon and there was fire … I saw corpses."
Photos of the accident site published on Spanish media websites and Twitter showed overturned train carriages, train cars on fire and bodies covered with blankets.
This CCTV camera footage shows the moment the train derailed:
The accident is Spain's first on its large network of high-speed railways, and its most deadly in years.
"Everything right now points to an accident," he said.
BBC reported that one of the train's drivers was put under formal investigation after the derailment.
The Associated Press said analysis of the video showed the train traveling well above the track's speed limit of 50 mph. An estimate of the speed, based on the distance between the pylons, would yield a range of 89 to 119 mph, said the AP.
As The Journal pointed out, "Although it wasn't one of Spain's highest speed bullet trains called AVEs, it was a relatively luxurious version that uses the same kind of track as Spain's fastest expresses."
US President Barack Obama said, "Michelle and I were shocked and saddened by the news of yesterday's tragic train derailment in Santiago de Compostela, Spain."
"On behalf of the American people, we offer our deepest sympathies and condolences to the families and loved ones of the more than 80 people who lost their lives," Obama added.
At least one American was among those killed, according to the State Department. Five others were injured, but the State Department said the numbers could change.
Obama said, "Today the American people grieve with our Spanish friends, who are in our thoughts and prayers. We stand ready to provide any assistance we can in the difficult days ahead."
Santiago de Compostela — whose historic old town is a UNESCO World Heritage Site and popular destination for Christian pilgrims — had been due to celebrate its namesake, Saint James, in an annual festival on Thursday. The city has canceled the event.
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