A Spanish train that hurtled off the rails and smashed into a security wall as it rounded a bend was going so fast that carriages tumbled off the tracks like dominoes, killing 80 people, according to witness accounts and video footage obtained Thursday.

An Associated Press analysis of video images suggests that the train may have been traveling at twice the speed limit for that stretch of track.

Spain’s government said two investigations have been launched into the cause of Wednesday night’s crash near Santiago de Compostela, a site of Christian pilgrimage in the Galicia region of northwestern Spain. The regional government confirmed that police planned to question the 52-year-old train driver, who is in a hospital with unspecified injuries, as both a witness and a possible suspect, but it cautioned that possible faults in safety equipment also were being investigated.

The Interior Ministry raised the death toll to 80 in the crash, Spain’s deadliest train wreck in four decades. The Galician government said 94 people remained hospitalized in six regional hospitals, 31 of them — including four children — in critical condition.

The U.S. State Department said one American was killed in the crash and five were injured, adding that those numbers were “likely to change.”

Ana-Maria Cordoba, who worked for Virginia’s Arlington Diocese, was among those killed, the Catholic News Service reported. Cordoba was traveling with her husband and daughter.

“Today the American people grieve with our Spanish friends, who are in our thoughts and prayers,” President Obama said in a statement.

Prime Minister Mariano Rajoy, a native of Santiago de Compostela, toured the crash scene alongside rescue workers and went to a nearby hospital to visit the injured and their families.

“For a native of Santiago, like me, this is the saddest day,” said Rajoy, who declared that Spain would observe a three-day period of mourning. He said judicial authorities and the Public Works Ministry had launched parallel investigations.

Witness accounts backed by security-­camera footage of the moment when the crash occurred suggested that the eight-carriage train was going too fast as it tried to bear left underneath a road bridge. The train company Renfe said 218 passengers and five crew members were on board. Spanish officials said the speed limit on that section of track is 50 mph.

An Associated Press estimate of the train’s speed at the moment of impact using the time stamp of the video and the estimated distance between two pylons gives a range of 89 to 119 mph. Another estimate calculated on the basis of the typical distance between railroad ties gives a range of 96 to 112 mph.

The video footage, which the Spanish railway authority Adif said probably came from one of its cameras, shows the carriages starting to buckle soon into the turn.

Murray Hughes, consultant editor of Railway Gazette International, said it appeared that a diesel-­powered unit behind the lead locomotive was the first to derail. The front engine quickly followed. In the background, all the rear carriages could be seen starting to decouple and come off the tracks. The picture went blank as the engine appeared to crash directly into the camera.

The Interior Ministry, responsible for law and order, ruled out terrorism as a cause.

— Associated Press