Santiago de Compostela, Spain (CNN) — The train races into view, and in the space of a heartbeat, the cars derail and crash into a wall of concrete, flipping onto their sides and skidding along the track with terrifying speed and force. Security footage shows the horror of the moment an express train derailed as it hurtled around a curve in northwestern Spain on Wednesday, killing at least 78 people and injuring 178, local officials said. Flames burst out of one train car as another car was snapped in half after the crash. Rescue crews and fellow passengers pulled bodies through broken windows and pried open doors as stunned survivors looked on. Investigations into the cause of the crash continue, but suggestions that the train was traveling too fast appear to be gaining weight.

The train driver is being questioned by police and under formal investigation, said María Pardo Rios, a spokeswoman for the Galicia regional supreme court. “He is not being charged by a judge at the moment — it is all at a police level,” she said. Ninety-five of the 178 injured are still hospitalized, the local government’s official Twitter account said. Thirty-two adults and four children are in critical condition. At least 73 people died at the scene and the others at the hospital, Rios said. In Spain, judges typically record deaths that take place outside of hospitals.

Judicial teams are still at the crash site and expect to find more bodies, she told CNN on Thursday morning. At least five Americans were injured in the crash, a U.S. State Department official said Thursday. The U.S. Embassy in Madrid is trying to determine the exact number. “At this time, we have not received any reports of U.S. citizen deaths,” the official said. Interim charge d’affaires Luis G. Moreno at the embassy said it was in touch “with families of some injured American citizens.” “We are deeply shocked by the news of last night’s train crash in Galicia. Our hearts and prayers are with the friends and families of the victims,” he said. UK Foreign Secretary William Hague said one British citizen was injured.

Train’s speed questioned

The state railway, Renfe, said the train crashed on a curve several kilometers from the train station in the city of Santiago de Compostela. The train had 218 passengers aboard and was nearing the end of a six-hour trip from Madrid to the town of Ferrol in northwest Spain when it derailed at 8:41 p.m. Wednesday, the railway said. It was unclear how fast the train was traveling when it crashed. It was capable of going up to 250 kilometers per hour (155 mph), said Julio Hermida, a spokesman for the state railway. The driver, who suffered minor injuries, told police he had entered the bend too fast, TVE reported. Rafael Catala, secretary of state for transport and housing, told Spanish radio network Cadena SER that the “tragedy appears to be linked to the train going too fast,” but that the reasons for that are not yet known. The president of Renfe, Julio Gomez-Pomar, told radio station COPE on Thursday that the train had undergone a routine inspection that same morning. “The train did not have an operating problem,” he said. “The maintenance and control record of the train was perfect.”

Mourning declared

Alberto Nunez Feijoo, head of the regional government in Galicia, declared seven days of mourning in the region for victims of the tragedy. Spanish Prime Minister Mariano Rajoy viewed the scene of devastation Thursday morning and visited some of the hospitalized crash victims. Rajoy, who is from the area, told a news conference there was a “huge challenge” ahead, not least in identifying all those killed and informing their families, and he praised the response of everyone who has helped after the crash. Two investigations are under way, he said, adding, “We want to establish what happened and find out what exactly were the causes of this serious rail accident.” Rajoy declared three days of national mourning to honor the victims of the crash.

The prime minister came under fire in Spanish media after a condolences message for the train crash victims posted by his office late Wednesday included a paragraph apparently “copied and pasted” from a statement previously sent to victims of an earthquake in Gansu, China.
”I would like to express my deepest condolences for the loss of human lives and the material damage from the earthquake that has occurred in Gansu has caused,” the note said.

Thunderous bang

A passenger who got off at the last stop before the train derailed told the broadcaster it was packed with people at the time. Residents who lived near the tracks told the Voz de Galicia newspaper that they heard a thunderous bang when the train crashed. Many of them rushed to the area with blankets and bottled water for the injured, the newspaper reported. “The train had broken in half. Some pieces were on top, some pieces were on the bottom,” said Ivette Rubiera Cabrera of Florida, who caught a glimpse of the wreckage while on a family vacation in Spain and sent photos to CNN’s iReport. “It was quite shocking,” she said. “We had never seen anything like that. We had just been on the train last week.” Oscar Mateos told Spain’s El Pais newspaper that he saw fellow passengers thrown to the floor, then tossed from one side of the train to the other. “Help came in five minutes, but that time became an eternity,” he said. “I helped people get out with broken legs and many bruises.” Alen Perez, 16, said he had been walking nearby and saw passengers helping each other out of the train. Emergency vehicles swarmed the scene. There were several bodies on the ground, he said. Photos he took of the crash site showed mangled pieces of a train car and black smoke billowing out of the wreckage.

Crash investigation

Investigators are looking at all possible causes of the crash, a senior aide to the prime minister said Wednesday. An initial assessment indicated it probably wasn’t an act of terrorism. Renfe’s spokesman said he did not know how many crew members were aboard the train when it crashed. Normally, there would be at least five crew members on a train like that, he said. Officials appealed for blood donations just after the crash but on Thursday said the short-term needs were met. The crash occurred shortly before a large annual celebration was set to start in Santiago de Compostela, a popular tourist destination. Local officials canceled festivities planned for Wednesday night and Thursday. Spain’s King Juan Carlos said the accident had saddened the country and the international community, and he sent a message to the victims and their families conveying “the deepest love and all the solidarity from the Royal Family, and from the whole nation. “Herman Van Rompuy, president of the European Council, also expressed condolences from the European Union. Pope Francis, currently on a visit to Brazil for World Youth Day, sent a telegram to the bishop of Santiago de Compostela, Julian Barrio Barrio, offering his support and prayers for all those affected by the tragedy.

CNN’s Al Goodman reported from Madrid. CNN’s Catherine E. Shoichet reported from Atlanta, and CNN’s Laura Smith-Spark wrote in London. CNN’s Elwyn Lopez, Patrick Sung, Eric Marrapodi, Jill Dougherty, Nelson Quinones, Marysabel Huston-Crespo and David Valenzuela contributed to this report.